Question

What is the completely factored form of f(x)=x^3+5x^2+16x+80 ?

f(x)=(x−5)(x−4i)(x+4i)

f(x)=(x+5)(x−4i)(x+4i)

f(x)=(x−5)(x−4)(x+4)

f(x)=(x+5)(x−4)(x+4)

Answer 1

B)
`f(x)=(x+5)(x-4i)(x+4i)`

Explanation:

`f(x)=x^3+5x^2+16x+80\\\\f(x)=x^2(x+5)+16(x+5)\\\\f(x)=(x^2+16)(x+5)\\\\f(x)=(x-4i)(x+4i)(x+5)`

Thus, the second choice is correct.