# Thread: Prepping for the GRE... It's been a while. Need a refresher on f(x)

1. ## Prepping for the GRE... It's been a while. Need a refresher on f(x)

Hey everyone!

I'm here because I'm getting ready to write the GRE, and I'm stumped, since it's been 9 years since I did any math. (Though I was good at it back in the day!)

"The function f is defined for all numbers x by f(x) = x2 + x. If t is a number such that f (2t) = 30, which two of the following could be the number t?
Indicate two such numbers.
(Multiple choice: -5, -3, -1/2, 2, 5/2)"

2. ## Re: Prepping for the GRE... It's been a while. Need a refresher on f(x)

Originally Posted by jodester516
Hey everyone!

I'm here because I'm getting ready to write the GRE, and I'm stumped, since it's been 9 years since I did any math. (Though I was good at it back in the day!)

"The function f is defined for all numbers x by f(x) = x2 + x. If t is a number such that f (2t) = 30, which two of the following could be the number t?
You are given a formula for f(x) and asked about f(2t). Replace each "x" in the formula by "2t" and do the algebra.

Indicate two such numbers.
(Multiple choice: -5, -3, -1/2, 2, 5/2)"