Question 131·Medium·Systems of Two Linear Equations in Two Variables
The ordered pair is the solution to the following system of equations:
What is the value of ?
When both equations in a system are already solved for (in the form ), quickly set the right-hand sides equal to form a single equation in , then solve. To save time and reduce mistakes, clear any fractions by multiplying through by a common denominator, combine like terms carefully—especially signs—and only at the end match your computed x-value to the answer choices.
Hints
Use the fact that both equations equal y
Since both equations are written as (something), think about what you can do with the two right-hand sides to relate them directly.
Form a single equation in x
Set equal to and rewrite this as one equation involving only .
Make the arithmetic easier
To get rid of the denominators 4, try multiplying both sides by 4. Then combine like terms and solve step by step for .
Finishing the solve
After simplifying, you should reach an equation like or . Make sure you complete the final step to isolate .
Desmos Guide
Enter both lines
In Desmos, type y = (3/4)x + 2 on one line and y = (1/4)x - 6 on another so both lines are graphed.
Find the intersection point
Look for the point where the two lines cross. Tap or click that intersection point; Desmos will display its coordinates .
Use the x-coordinate as your answer
Read the x-coordinate of the intersection point from Desmos. That x-value is the solution to the system and the correct choice among the options.
Step-by-step Explanation
Set the equations equal to each other
Both expressions are equal to , so they must be equal to each other:
Clear the fractions
To avoid working with fractions, multiply both sides of the equation by 4:
This simplifies to:
Collect like terms and isolate the x-term
Get all the terms on one side and the constants on the other.
Subtract from both sides:
So:
Now subtract 8 from both sides:
Solve for x and choose the matching option
Divide both sides of by 2:
So the value of is , which corresponds to choice A.