Question

If f (x) = – 4x3 + 2x2 – 1, find f (– 1)

Answer 1

`f(-1)=5`

Explanation:

We know that the equation is

`f(x)=-4x^3+2x^2-1`

We can then plug -1 in for x

`f(-1)=-4(-1)^3+2(-1)^2-1\\\\f(-1)=-4(-1)+2(1)-1\\\\f(-1)=4+2-1\\\\f(-1)=5`

Answer 2

`f( - 1) = 5`

EXPLANATION

The given function is

`f(x) = - 4 {x}^(3) + 2 {x}^(2) - 1`

We substitute x=-1 to obtain:

`f( - 1) = - 4 {( - 1)}^(3) + 2 {( - 1)}^(2) - 1`

We simplify to obtain;

`f( - 1) = 4 + 2 - 1`

.

This evaluates to

`f( - 1) = 5`