Question

for the polynomial function f(x) = -0.02x^4 + .36x^2 - 1.63, fina all local and global extrema.
the only extrema point is (9,0)
no local extrema exist
the only extrema point is (-1.62. 0)
the local and global extrema are: (-3,0),(0, -1.62) and (3,0)