Find f(x-1) when f(x)=5x^2 +2x+4

Answer 1

Hi Caimee! Let's take a look at this problem...

When we want to evaluate a function at a particular value, we have to substitute in the value desired where we see x in the original function. In this case, we'll substitute all of the x's in the function with (x-1).

So originally, f(x) = 5x^2 +2x + 4

f(x-1) = 5(x-1)^2 + 2(x-1) + 4

Let's go ahead and expand the quadratic...

f(x-1) = 5(x^2-2x+1) + 2x - 2 + 4

= 5x^2 - 10x + 5 + 2x - 2 +4

= 5x^2 - 8x + 7

Hope that helps!