Find the roots of the function g(x)=x^3 +16x

Question

a)0,4i, -4i
b)0,-4,-4i
c)0,4,4i
d)0,4,-4

The equation can be rewritten
x(x^2 + 16) = 0
The function is zero if x = 0, OR if
x^2 = -16
That should give you a hint of what the roots are.

So you take the square root of -16 which gives you +- 4 making the answer d. Right?

No. The square root of -16 is 4i and -41.

i = sqrt (-1)

The answer is (a). I mistakenly typed
-41 for -4i