Question

Find All real Zeros of the function

f(x) = x^3 -31x -30

I know the answers are -5, -1, and 6 (to book told me) but I think I may be doing something wrong when solving because I cant seem to get the answers!

All of the possible x values could be + or - (1,2,3,5,6,15,30)

To solve I have to use synthetic division. Please help!

Answer 1

@SnuggieLad

Answer 2

f(x) can be factored:\[x^3-31 x-30=(x-6) (x+1) (x+5) \]

Answer 3

A plot is attached.