Functions look complicated but are in fact very easy once you understand how they work. A function maps or sends a number to another number.
Take for example the function g. Let g be defined as g(x) = x + 4.5 This means that when you apply the function “g” to any number “x”, it adds 4.5 to x.
So g(20) = 20 + 4.5 = 24.5
and g(0) = 0 + 4.5 = 4.5
The key is to replace “x” with whatever you see in the brackets. For example, if the function f was defined as f(x) = x2 – 2x +4, you can find f(2) by replacing “x” with “2” everywhere.
So f(2) = (2)2 -2(2) + 4 = 4 – 4 + 4 = 4
Suppose I want to find f(2n). Then I would replace x with 2n and get
f(2n) = (2n)2 -2(2n) + 4 = 4n2 -4n +4
Test your knowledge with this SAT Math question!
