Practice
Solving Systems Consisting of Linear and Quadratic Equations Practice
Fifty original questions on substitution, ordered pairs, intersection counts, tangency, quadratic pairs, parameters, and exact graphs.
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Question 1
Explanation
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=-2\) and \(x=3\), then substitute each into the line. This yields \((-2,0)\text{ and }(3,5)\), and both pairs satisfy both equations.
- Method
A system solution is an ordered pair, so recover the output for every quadratic root.
- Conclusion
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=-2\) and \(x=3\), then substitute each into the line. This yields \((-2,0)\text{ and }(3,5)\), and both pairs satisfy both equations.
Question 2
Explanation
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=-1\) and \(x=4\), then substitute each into the line. This yields \((-1,5)\text{ and }(4,0)\), and both pairs satisfy both equations.
- Method
A system solution is an ordered pair, so recover the output for every quadratic root.
- Conclusion
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=-1\) and \(x=4\), then substitute each into the line. This yields \((-1,5)\text{ and }(4,0)\), and both pairs satisfy both equations.
Question 3
Explanation
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=0\) and \(x=5\), then substitute each into the line. This yields \((0,-1)\text{ and }(5,9)\), and both pairs satisfy both equations.
- Method
A system solution is an ordered pair, so recover the output for every quadratic root.
- Conclusion
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=0\) and \(x=5\), then substitute each into the line. This yields \((0,-1)\text{ and }(5,9)\), and both pairs satisfy both equations.
Question 4
Explanation
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=-3\) and \(x=2\), then substitute each into the line. This yields \((-3,9)\text{ and }(2,-1)\), and both pairs satisfy both equations.
- Method
A system solution is an ordered pair, so recover the output for every quadratic root.
- Conclusion
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=-3\) and \(x=2\), then substitute each into the line. This yields \((-3,9)\text{ and }(2,-1)\), and both pairs satisfy both equations.
Question 5
Explanation
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=1\) and \(x=6\), then substitute each into the line. This yields \((1,4)\text{ and }(6,19)\), and both pairs satisfy both equations.
- Method
A system solution is an ordered pair, so recover the output for every quadratic root.
- Conclusion
Set the two expressions for \(y\) equal, solve the resulting quadratic to get \(x=1\) and \(x=6\), then substitute each into the line. This yields \((1,4)\text{ and }(6,19)\), and both pairs satisfy both equations.
Question 6
Explanation
Substitute \(x=-1\) into the quadratic: \(k=1(-1)^2+-3(-1)+-4=0\). A shared point must use this output coordinate.
- Method
A missing coordinate is found by substitution, not by reading unrelated coefficients.
- Conclusion
Substitute \(x=-1\) into the quadratic: \(k=1(-1)^2+-3(-1)+-4=0\). A shared point must use this output coordinate.
Question 7
Explanation
Substitute \(x=2\) into the quadratic: \(k=1(2)^2+2(2)+-8=0\). A shared point must use this output coordinate.
- Method
A missing coordinate is found by substitution, not by reading unrelated coefficients.
- Conclusion
Substitute \(x=2\) into the quadratic: \(k=1(2)^2+2(2)+-8=0\). A shared point must use this output coordinate.
Question 8
Explanation
Substitute \(x=5\) into the quadratic: \(k=-1(5)^2+4(5)+5=0\). A shared point must use this output coordinate.
- Method
A missing coordinate is found by substitution, not by reading unrelated coefficients.
- Conclusion
Substitute \(x=5\) into the quadratic: \(k=-1(5)^2+4(5)+5=0\). A shared point must use this output coordinate.
Question 9
Explanation
Substitute \(x=1\) into the quadratic: \(k=2(1)^2+-6(1)+1=-3\). A shared point must use this output coordinate.
- Method
A missing coordinate is found by substitution, not by reading unrelated coefficients.
- Conclusion
Substitute \(x=1\) into the quadratic: \(k=2(1)^2+-6(1)+1=-3\). A shared point must use this output coordinate.
Question 10
Explanation
Substitute \(x=-3\) into the quadratic: \(k=-2(-3)^2+-4(-3)+6=0\). A shared point must use this output coordinate.
- Method
A missing coordinate is found by substitution, not by reading unrelated coefficients.
- Conclusion
Substitute \(x=-3\) into the quadratic: \(k=-2(-3)^2+-4(-3)+6=0\). A shared point must use this output coordinate.
Question 11
Explanation
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 0 real roots, matching the 0 graph intersections.
- Method
Count graph intersections and confirm the count with the reduced quadratic's discriminant.
- Conclusion
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 0 real roots, matching the 0 graph intersections.
Question 12
Explanation
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 1 real root, matching the 1 graph intersection.
- Method
Count graph intersections and confirm the count with the reduced quadratic's discriminant.
- Conclusion
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 1 real root, matching the 1 graph intersection.
Question 13
Explanation
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 2 real roots, matching the 2 graph intersections.
- Method
Count graph intersections and confirm the count with the reduced quadratic's discriminant.
- Conclusion
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 2 real roots, matching the 2 graph intersections.
Question 14
Explanation
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 2 real roots, matching the 2 graph intersections.
- Method
Count graph intersections and confirm the count with the reduced quadratic's discriminant.
- Conclusion
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 2 real roots, matching the 2 graph intersections.
Question 15
Explanation
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 0 real roots, matching the 0 graph intersections.
- Method
Count graph intersections and confirm the count with the reduced quadratic's discriminant.
- Conclusion
Substitution produces a quadratic whose real roots correspond to the plotted intersection points. It has 0 real roots, matching the 0 graph intersections.
Question 16
Explanation
The marked intersections are \((-1,0)\text{ and }(2,3)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
- Method
Read both coordinates at each intersection and verify them algebraically.
- Conclusion
The marked intersections are \((-1,0)\text{ and }(2,3)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
Question 17
Explanation
The marked intersections are \((-2,4)\text{ and }(3,-1)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
- Method
Read both coordinates at each intersection and verify them algebraically.
- Conclusion
The marked intersections are \((-2,4)\text{ and }(3,-1)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
Question 18
Explanation
The marked intersections are \((0,0)\text{ and }(4,8)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
- Method
Read both coordinates at each intersection and verify them algebraically.
- Conclusion
The marked intersections are \((0,0)\text{ and }(4,8)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
Question 19
Explanation
The marked intersections are \((-1,7)\text{ and }(5,-5)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
- Method
Read both coordinates at each intersection and verify them algebraically.
- Conclusion
The marked intersections are \((-1,7)\text{ and }(5,-5)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
Question 20
Explanation
The marked intersections are \((1,1)\text{ and }(3,7)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
- Method
Read both coordinates at each intersection and verify them algebraically.
- Conclusion
The marked intersections are \((1,1)\text{ and }(3,7)\). Substitution confirms that each ordered pair satisfies both the line and parabola equations.
Question 21
Explanation
A horizontal tangent occurs at the vertex. The vertex is \((2,3)\), so the tangent line is \(y=3\). Equivalently, substitution makes the reduced discriminant zero.
- Method
For a horizontal tangent, find the parabola's extreme output value.
- Conclusion
A horizontal tangent occurs at the vertex. The vertex is \((2,3)\), so the tangent line is \(y=3\). Equivalently, substitution makes the reduced discriminant zero.
Question 22
Explanation
A horizontal tangent occurs at the vertex. The vertex is \((-2,-5)\), so the tangent line is \(y=-5\). Equivalently, substitution makes the reduced discriminant zero.
- Method
For a horizontal tangent, find the parabola's extreme output value.
- Conclusion
A horizontal tangent occurs at the vertex. The vertex is \((-2,-5)\), so the tangent line is \(y=-5\). Equivalently, substitution makes the reduced discriminant zero.
Question 23
Explanation
A horizontal tangent occurs at the vertex. The vertex is \((-3,2)\), so the tangent line is \(y=2\). Equivalently, substitution makes the reduced discriminant zero.
- Method
For a horizontal tangent, find the parabola's extreme output value.
- Conclusion
A horizontal tangent occurs at the vertex. The vertex is \((-3,2)\), so the tangent line is \(y=2\). Equivalently, substitution makes the reduced discriminant zero.
Question 24
Explanation
A horizontal tangent occurs at the vertex. The vertex is \((2,-7)\), so the tangent line is \(y=-7\). Equivalently, substitution makes the reduced discriminant zero.
- Method
For a horizontal tangent, find the parabola's extreme output value.
- Conclusion
A horizontal tangent occurs at the vertex. The vertex is \((2,-7)\), so the tangent line is \(y=-7\). Equivalently, substitution makes the reduced discriminant zero.
Question 25
Explanation
A horizontal tangent occurs at the vertex. The vertex is \((5,-9)\), so the tangent line is \(y=-9\). Equivalently, substitution makes the reduced discriminant zero.
- Method
For a horizontal tangent, find the parabola's extreme output value.
- Conclusion
A horizontal tangent occurs at the vertex. The vertex is \((5,-9)\), so the tangent line is \(y=-9\). Equivalently, substitution makes the reduced discriminant zero.
Question 26
Explanation
Set the functions equal and simplify. The resulting quadratic has roots \(-2\) and \(2\). Substitution gives \((-2,3)\text{ and }(2,3)\), and each pair satisfies both quadratics.
- Method
Set the two expressions equal, solve for inputs, then recover and verify each output.
- Conclusion
Set the functions equal and simplify. The resulting quadratic has roots \(-2\) and \(2\). Substitution gives \((-2,3)\text{ and }(2,3)\), and each pair satisfies both quadratics.
Question 27
Explanation
Set the functions equal and simplify. The resulting quadratic has roots \(-3\) and \(1\). Substitution gives \((-3,3)\text{ and }(1,3)\), and each pair satisfies both quadratics.
- Method
Set the two expressions equal, solve for inputs, then recover and verify each output.
- Conclusion
Set the functions equal and simplify. The resulting quadratic has roots \(-3\) and \(1\). Substitution gives \((-3,3)\text{ and }(1,3)\), and each pair satisfies both quadratics.
Question 28
Explanation
Set the functions equal and simplify. The resulting quadratic has roots \(-1\) and \(4\). Substitution gives \((-1,6)\text{ and }(4,11)\), and each pair satisfies both quadratics.
- Method
Set the two expressions equal, solve for inputs, then recover and verify each output.
- Conclusion
Set the functions equal and simplify. The resulting quadratic has roots \(-1\) and \(4\). Substitution gives \((-1,6)\text{ and }(4,11)\), and each pair satisfies both quadratics.
Question 29
Explanation
Set the functions equal and simplify. The resulting quadratic has roots \(-4\) and \(1\). Substitution gives \((-4,18)\text{ and }(1,3)\), and each pair satisfies both quadratics.
- Method
Set the two expressions equal, solve for inputs, then recover and verify each output.
- Conclusion
Set the functions equal and simplify. The resulting quadratic has roots \(-4\) and \(1\). Substitution gives \((-4,18)\text{ and }(1,3)\), and each pair satisfies both quadratics.
Question 30
Explanation
Set the functions equal and simplify. The resulting quadratic has roots \(0\) and \(5\). Substitution gives \((0,1)\text{ and }(5,6)\), and each pair satisfies both quadratics.
- Method
Set the two expressions equal, solve for inputs, then recover and verify each output.
- Conclusion
Set the functions equal and simplify. The resulting quadratic has roots \(0\) and \(5\). Substitution gives \((0,1)\text{ and }(5,6)\), and each pair satisfies both quadratics.
Question 31
Explanation
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(x^2+x-8=0\).
- Method
Reduce the system to one equation before using factoring or the quadratic formula.
- Conclusion
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(x^2+x-8=0\).
Question 32
Explanation
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(2x^2-6x+6=0\).
- Method
Reduce the system to one equation before using factoring or the quadratic formula.
- Conclusion
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(2x^2-6x+6=0\).
Question 33
Explanation
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(x^2-3x-6=0\).
- Method
Reduce the system to one equation before using factoring or the quadratic formula.
- Conclusion
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(x^2-3x-6=0\).
Question 34
Explanation
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(3x^2+2x-6=0\).
- Method
Reduce the system to one equation before using factoring or the quadratic formula.
- Conclusion
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(3x^2+2x-6=0\).
Question 35
Explanation
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(2x^2-10x+2=0\).
- Method
Reduce the system to one equation before using factoring or the quadratic formula.
- Conclusion
Because both expressions equal \(y\), set them equal and move every term to one side. Combining like terms gives \(2x^2-10x+2=0\).
Question 36
Explanation
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 1 real root, so the graphs have 1 real intersection.
- Method
When only the number of intersections is requested, the reduced discriminant is sufficient.
- Conclusion
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 1 real root, so the graphs have 1 real intersection.
Question 37
Explanation
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 0 real roots, so the graphs have 0 real intersections.
- Method
When only the number of intersections is requested, the reduced discriminant is sufficient.
- Conclusion
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 0 real roots, so the graphs have 0 real intersections.
Question 38
Explanation
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 2 real roots, so the graphs have 2 real intersections.
- Method
When only the number of intersections is requested, the reduced discriminant is sufficient.
- Conclusion
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 2 real roots, so the graphs have 2 real intersections.
Question 39
Explanation
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 1 real root, so the graphs have 1 real intersection.
- Method
When only the number of intersections is requested, the reduced discriminant is sufficient.
- Conclusion
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 1 real root, so the graphs have 1 real intersection.
Question 40
Explanation
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 2 real roots, so the graphs have 2 real intersections.
- Method
When only the number of intersections is requested, the reduced discriminant is sufficient.
- Conclusion
Substitution gives a one-variable quadratic. Its discriminant has the sign corresponding to 2 real roots, so the graphs have 2 real intersections.
Question 41
Explanation
Setting the two quadratics equal produces the marked input values; substitution gives \((-2,0)\text{ and }(2,0)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
- Method
For graph-based systems, verify each marked intersection in both equations.
- Conclusion
Setting the two quadratics equal produces the marked input values; substitution gives \((-2,0)\text{ and }(2,0)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
Question 42
Explanation
Setting the two quadratics equal produces the marked input values; substitution gives \((-3.236,1)\text{ and }(1.236,1)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
- Method
For graph-based systems, verify each marked intersection in both equations.
- Conclusion
Setting the two quadratics equal produces the marked input values; substitution gives \((-3.236,1)\text{ and }(1.236,1)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
Question 43
Explanation
Setting the two quadratics equal produces the marked input values; substitution gives \((-1.732,4)\text{ and }(1.732,4)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
- Method
For graph-based systems, verify each marked intersection in both equations.
- Conclusion
Setting the two quadratics equal produces the marked input values; substitution gives \((-1.732,4)\text{ and }(1.732,4)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
Question 44
Explanation
Setting the two quadratics equal produces the marked input values; substitution gives \((-1.236,3)\text{ and }(3.236,3)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
- Method
For graph-based systems, verify each marked intersection in both equations.
- Conclusion
Setting the two quadratics equal produces the marked input values; substitution gives \((-1.236,3)\text{ and }(3.236,3)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
Question 45
Explanation
Setting the two quadratics equal produces the marked input values; substitution gives \((-4.828,5)\text{ and }(0.828,5)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
- Method
For graph-based systems, verify each marked intersection in both equations.
- Conclusion
Setting the two quadratics equal produces the marked input values; substitution gives \((-4.828,5)\text{ and }(0.828,5)\). Every displayed point satisfies both equations, so all 2 ordered pairs are retained.
Question 46
Explanation
System solutions require ordered pairs, so each corresponding output must be found. Substitution into both original equations is the final validity test for every proposed ordered pair.
- Method
Track inputs and outputs together, and verify both original equations.
- Conclusion
System solutions require ordered pairs, so each corresponding output must be found. Substitution into both original equations is the final validity test for every proposed ordered pair.
Question 47
Explanation
Each real root must be substituted back because each can produce an intersection. Substitution into both original equations is the final validity test for every proposed ordered pair.
- Method
Track inputs and outputs together, and verify both original equations.
- Conclusion
Each real root must be substituted back because each can produce an intersection. Substitution into both original equations is the final validity test for every proposed ordered pair.
Question 48
Explanation
A system solution must satisfy both equations, so the point is invalid. Substitution into both original equations is the final validity test for every proposed ordered pair.
- Method
Track inputs and outputs together, and verify both original equations.
- Conclusion
A system solution must satisfy both equations, so the point is invalid. Substitution into both original equations is the final validity test for every proposed ordered pair.
Question 49
Explanation
First reduce the system to a one-variable quadratic, then compute its discriminant. Substitution into both original equations is the final validity test for every proposed ordered pair.
- Method
Track inputs and outputs together, and verify both original equations.
- Conclusion
First reduce the system to a one-variable quadratic, then compute its discriminant. Substitution into both original equations is the final validity test for every proposed ordered pair.
Question 50
Explanation
After algebraic verification, apply the stated contextual domain restriction. Substitution into both original equations is the final validity test for every proposed ordered pair.
- Method
Track inputs and outputs together, and verify both original equations.
- Conclusion
After algebraic verification, apply the stated contextual domain restriction. Substitution into both original equations is the final validity test for every proposed ordered pair.
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Questions to review
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- Question 7Finding a missing system coordinateEasy
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- Question 12Graphical system solution countEasy
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- Question 14Graphical system solution countEasy
- Question 15Graphical system solution countEasy
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- Question 17Reading ordered-pair intersectionsMedium
- Question 18Reading ordered-pair intersectionsMedium
- Question 19Reading ordered-pair intersectionsMedium
- Question 20Reading ordered-pair intersectionsMedium
- Question 21Tangency parameterMedium
- Question 22Tangency parameterMedium
- Question 23Tangency parameterMedium
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- Question 25Tangency parameterMedium
- Question 26Solving a quadratic-quadratic systemMedium
- Question 27Solving a quadratic-quadratic systemMedium
- Question 28Solving a quadratic-quadratic systemMedium
- Question 29Solving a quadratic-quadratic systemMedium
- Question 30Solving a quadratic-quadratic systemMedium
- Question 31Reducing a system by substitutionMedium
- Question 32Reducing a system by substitutionMedium
- Question 33Reducing a system by substitutionMedium
- Question 34Reducing a system by substitutionMedium
- Question 35Reducing a system by substitutionMedium
- Question 36Discriminant for system solution countMedium
- Question 37Discriminant for system solution countMedium
- Question 38Discriminant for system solution countMedium
- Question 39Discriminant for system solution countMedium
- Question 40Discriminant for system solution countMedium
- Question 41Two-parabola graph validationHard
- Question 42Two-parabola graph validationHard
- Question 43Two-parabola graph validationHard
- Question 44Two-parabola graph validationHard
- Question 45Two-parabola graph validationHard
- Question 46Quadratic-system error analysisHard
- Question 47Quadratic-system error analysisHard
- Question 48Quadratic-system error analysisHard
- Question 49Quadratic-system error analysisHard
- Question 50Quadratic-system error analysisHard