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GMAT Functions

by ejkiv


July 19, 2015


GMAT functions are really just fancy ways to write out equations. There is no reason for you to be scared of this question type (I know I sound like a broken record on this, but it is true). Functions look like this:

f(x)= x+1

This pronounced ‘f of x equals x plus 1.‘ Really, you can think of the f(x) portion of this as you would the variable y in a linear equation. The main difference is that the value inside the parenthesis will tell you what to plug into the x variable. So, for this function:

f (8) = 8 + 1 = 9

See, that is not so bad.  All you are doing is replacing any 'x' that you see on the right side of the equation with what is inside the parenthesis. Try f(x-2):

f(x−2)=(x−2)+1= x−1

Or even another more complicated example:

If f(x)=x^2 −x,

Then f(x+1)=(x+1)^2 −(x+1) = x^2 +2x+1−x−1 = x^2 +x.

Functions will not always be written as f(x); functions might be written as g(x) or even h(x). Another layer would be to have an embedded function, or a function within a function. While this may seem scary, it is easy if you follow the order of operations and work from the inside parenthesis first. Take this example:

If g(x)= x+2x, then what is g(g(2))?

First, solve the innermost function:

g(2) = (2) + 2(2) = 6

Then, plug the solution into the function again:

g(6) = (6) + 2(6) = 18

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