Question 92·Medium·Linear Equations in One Variable
If satisfies the equation above, what is the value of ?
For linear equations with parentheses, first distribute to remove the parentheses, then combine like terms on each side before trying to isolate the variable. Once the equation is simplified, move all x terms to one side and constants to the other, solve for , and only then plug that value into the expression the question asks about (here, ). Always re-read the final expression and handle fraction arithmetic carefully to avoid small sign or subtraction errors that lead to wrong choices designed to trap you.
Hints
Remove the parentheses first
Before solving for , use the distributive property to expand and so that there are no parentheses.
Combine like terms and isolate x
After distributing, combine the terms and the constant terms on each side to get a simpler equation, then move the terms to one side and the constants to the other.
Answer the question being asked
Once you find , remember the problem asks for . Substitute your value of into that expression and simplify carefully, especially with fractions.
Desmos Guide
Graph each side of the equation
In one expression line, type y = 5(4 - x) + 3x. In another line, type y = 2(x + 7) + 1. These represent the left and right sides of the equation as two lines.
Find the solution for x
Use Desmos to locate the intersection point of the two lines. Click on the intersection; the x-coordinate of this point is the value of that satisfies the equation.
Evaluate 2x − 5 using the x-value
Take the x-value from the intersection (step 2) and, in a new expression line, type 2*(that x-value) - 5. Desmos will display a numerical result; choose the answer option that has the same value as this result.
Step-by-step Explanation
Distribute to remove parentheses
Start with the equation:
Distribute on each side:
- Left side: , so .
- Right side: , so .
Now the equation is:
Solve the linear equation for x
Solve by getting terms on one side and constants on the other:
Now you know the value of ; the question, however, asks for , not itself.
Substitute x into 2x − 5 and simplify
Use in the expression :
Write as so you can subtract:
So the value of is , which corresponds to choice D.