If you would like to find the rational roots of x^4 + 8 * x^3 + 7 * x^2 - 40 * x - 60 = 0, you can do this using the following steps:
x^4 + 8 * x^3 + 7 * x^2 - 40 * x - 60 = 0
(x^2 - 5) * (x^2 + 8 * x + 12) = 0
(x^2 - 5) * (x + 6) * (x + 2) = 0
1. x = - sqrt(5)
2. x = sqrt(5)
3. x = - 6
4. x = - 2
The correct result would be -6 and -2.
8 x (5 x 2 + 3)=104 because 5 x 2 is 10, 10 + 3 is 13, and 13 x 8 is 104.