Question

Solve the equation f(x)=x3+2x2+4x+8 given that one of its roots is x=−2.

Answer 1

Okay, first you need to understand that function of x, (or f(x)) is y.

We now plug in x.

f(-2) or y=-2(3)+(2•2)+4(-2)+8
f(-2)=-6+4+-8+8

f(-2)=-2

When x=-2, y=-2. Lets plug it back in to see if its true.

-2=-2(3) + (2x2) + (4(-2)) + 8

-2 = -6 + 4 + -8 + 8

-2 = -2.

Heart if it helps, comment if you need help.