Finding x such that F(x) = 0.  Choose [a,b] such that F(a) and F(b) have opposite sign.
With "test" you find 10 values of F from a to b.

f(x) = h*x^4 + k*x^3 + p*x^2 + q*x + u
h k p q u

  a = b =  


examples