Complete the steps to solve the polynomial equation x3-21x=-20 according to the rational root theorem, which number is a potential root of the polynomial?

X^3 - 21x + 20 = 0

potential roots are factors of 20 eg 1, 2,4,5, 10, 20 and the negative values of these

1 looks like a rots. Try it:-

f (1) = 1 - 21 + 20 = - 20+20 = 0

Yes 1 is a solution.

2 is not.

Try 4:-

4^3 - 21*4 + 20 = 64 - 84 + 20 = 0

Try 5 No

Try 10 - N0

20 no.

Try - 4 - No

-5:-

Yes

Roots are 1, 4 and - 5