Question

f(x) = –4x3 + 4x

Answer 1

If f(x)= 4x -3, find the following:
f(-1)
What f(-1) tells you to do is to start with f(x) = 4x - 3, then replace every x you see
in it by (-1), and finally compute what the right side equals.
.
Let's change the problem a little and find f(-4). Go to the expression f(x) = 4x - 3 and
replace all the x's by -4. When you do the expression becomes:
.
f(-4) = 4(-4) - 3


.
When you multiply 4 times -4 you get -16. Substitute -16 for 4(-4) and the expression
becomes
.
f(-4) = -16 -3 and the two terms on the right combine so that the expression becomes:
.
f(-4) = -19
.
You can do the work to find f(-1). Follow the same process as the example.
.
I hope this helps you to understand what the problem really means.