Question

What are the possible number of positive, negative, and complex zeros of f(x) = –x6 – x5– x4 – 4x3 – 12x2 + 12 ?
Positive: 4, 2, or 0; Negative: 2 or 0; Complex: 6, 4, 2, or 0

Positive: 3 or 1; Negative: 3 or 1; Complex: 4, 2, or 0

Positive: 3 or 1; Negative: 2 or 0; Complex: 4, 2, or 0

Positive: 1; Negative: 5, 3, or 1; Complex: 4, 2, or 0

Answer 1

use descarte's rule of signs.
http://www.purplemath.com/modules/drofsign.htm

Answer 2

ditto -> http://www.youtube.com/watch?v=5YAmwfT3Esc