Question 175·Easy·Nonlinear Equations in One Variable; Systems in Two Variables
Which ordered pair is a solution to the system below?
For systems that include a nonlinear equation (like ) and a linear equation, use substitution if one variable is already isolated: replace that variable in the other equation and solve the resulting single-variable equation. Then compute the matching value of the other variable using the simpler equation, and finally check which of the resulting points appear among the answer choices. Always verify that your chosen point satisfies both original equations, not just one.
Hints
Think about what it means to solve a system
A solution to the system must make both equations true at the same time. That means the and values you choose must satisfy and together.
Use substitution
Because one equation already has by itself (), try substituting for in the other equation to get an equation in just .
Solve the resulting quadratic
After substitution, you will get a quadratic equation in . Factor it (or use another method) to find the possible -values, then plug back into to find for each.
Check against the answer choices
Once you have the possible pairs from solving the system, compare them with the four answer choices and pick the one that matches.
Desmos Guide
Graph both equations
In Desmos, enter the equations as two separate lines: y = x^2 and y = 6 - x. These represent the parabola and the line from the system.
Find the intersection points
Look for the points where the parabola and the line cross. Click on each intersection to see its coordinates; these are the solutions to the system.
Match with the answer choices
Compare the intersection coordinates you see in Desmos with the four answer choices and select the option that exactly matches one of those intersection points.
Step-by-step Explanation
Use substitution to combine the equations
You are told that and also that .
Since , substitute for in the second equation:
Rewrite this as a standard quadratic equation by moving all terms to one side:
Solve the quadratic equation for x
Factor the quadratic :
Set each factor equal to zero:
So the possible -values are and . Each gives a possible solution point.
Find the corresponding y-values
Use to find for each :
- If , then , so one possible solution is .
- If , then , so another possible solution is .
Both points satisfy the system, but you must choose from the given answer options.
Compare with the answer choices
Look at the listed options: , , , .
Only matches one of the solution points you found for the system (the other solution, , is not listed). Therefore, the correct answer is .