Let f(x) = 2x to the second power +5x-3
Find the values of f(0), f(-3), f(1/2), f(a), f(-b) and f (a-b)

Does anyone know the answer?

Whatever is in the parenthesis, substitute for x.

If f(x) = 2x then f(3) = (2)(3) =6

F(a-5) would be 2(a-5) or 2a-10 or a-5; that''s a strange answer

You try:

I think what he meant was this:



But as KISS suggests, just substitute whatever value of x you are given into the formula. We call this "plug and chug." For example, if x = 2, you have:



See how it works?

True. I knew that, I just took another simpler example and added the (a-5) case.