Question

F(x)=−5x3−4x2+8x and g(x)=−4x2+8, find (f−g)(x) and (f−g)(−2).

Answer 1

(f-g)(x) = -5x^3 + 8x - 8.

(f-g)(-2) = 16.

Explanation:

To find (f-g)(x), we need to subtract g(x) from f(x) and simplify:

(f-g)(x) = f(x) - g(x)

= (-5x^3 - 4x^2 + 8x) - (-4x^2 + 8)

= -5x^3 - 4x^2 + 8x + 4x^2 - 8

= -5x^3 + 8x - 8

Therefore, (f-g)(x) = -5x^3 + 8x - 8.

To find (f-g)(-2), we substitute x = -2 into the expression we just found:

(f-g)(-2) = -5(-2)^3 + 8(-2) - 8

= -5(-8) - 16 - 8

= 40 - 24

= 16

Therefore, (f-g)(-2) = 16.