Question

Wait, how is x=-1 not a double root?

Answer 1

Do you mean
\[
f'(x)=(x^2-4)(x+1)^2
\]
f ‘(x) has an x-intercept at x = -1 but x = -1 is not a relative extrema on the graph of f(x) because f'(x) does not change sign from before x=-1 to after x=-1. This is because
x=-1 is a double root.

Answer 2

Close the above problem and write your last problem as anew problem.

Answer 3

Do not forget to rate the best answer on the old problem.