3# complex zeros:
x = -2+5i
x = -2-5i
f(x) = (x -(-2+5i))(x - (-2-5i))
f(x) = (x+2-5i)(x+2+5i)
f(x) = x^2 +2x+5xi+2x+4+10i-5xi-10i-25i^2
f(x) = x^2 + 4x + 29
#4. factor
f(x) = x^4 + 6x^2 - 91
f(x) = (x^2 - 7)(x^2 + 13)
will have four solutions for fourth degree polynomial. +positive and -negative
x^2 - 7 = 0
x^2 = 7
x = +/- sqrt(7)
Has only one zero in interval.
x = sqrt(7) is a zero within [2,3]
