Plz show me step by step how to solve these equations ASAP. Tysm!
13. x^6-64x^4+x^2-7x-51; x=8
14. -x^3+3x^2+5x+1; x=-12
15. 2x^3+4x^2+6x+7; x=1/2
(Btw, 13, 14, and 15 are not part of each equation. They're are 3 of the numbers in the set of my algebra 2 hw.)