Functions

A function is a relation that assigns to each input number EXACTLY ONE output number. F(X) or G(X) or H(X) is the same as "Y"

For example if we have a function:

F(X) = 3X²-5 and we need F(2) , that means that in every X you need to substitute it for a 2.

F(2) = 3(2)²-5= 3(4) -5 = 12 -5 = 7, therefore when X= 2, 
then F(x)= 7 or Y=7

Let's practice:

If F(X)= 4X + 5, what is F(3) ?

F(3) = 4(3) + 5= 12 + 5= 17

When X=3, then Y= 17

What is F(-1) ?

F(-1) = 4(-1) + 5 = -4 + 5= 1

Translation: when X= -1 then Y= 1