BrentGMATPrepNow
What is the value of \(x\)?
(1) \(4(2x - 1.5y) - 3(1.5x - 2y) = -4.235\)
(2) \(3(2y - 1.5x) - 4(1.5y - 2x) = -4.235\)
I created this question to highlight a common misconception about linear equations.
Many students will look at the first equation and conclude that, since the equation has two variables, there's no way to determine the value of x.
However, if you simplify the first equation, you'll find that there's only one variable.
The same applies to the second equation. Target question: What is the value of \(x\)? Statement 1: \(4(2x - 1.5y) - 3(1.5x - 2y) = -4.235\) Expand to get: \(8x-6y - 4.5x + 6y = -4.235\)
Simplify: \(3.5x = -4.235\)
At this point, we can see that
\(x = \frac{-4.235}{3.5}\), which means statement 1 is sufficient.
Aside: On test day, we'd never waste valuable time actually calculating\(\frac{-4.235}{3.5}\). Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: \(3(2y - 1.5x) - 4(1.5y - 2x) = -4.235\)Expand to get: \(6y - 4.5x - 6y + 8x = -4.235\)
Simplify: \(3.5x = -4.235\)
This equation is identical to the simplified equation in statement 1.
So, statement 2 is SUFFICIENT
Answer: D
Cheers,
Brent