高次方程 help~~~~~~

1. f(x)=x^4 - 15x^2 + 10x + 24 = 0
要利用x^4系數和24的因數做分母和分子來做測試
先用-1做測試, put -1 into f(x) , f(-1)=0,根據factor theorem和除法,
x^4 - 15x^2 + 10x + 24 = 0
(x+1)(x^3-x^2-14x+24)=0
再用2來測試, put 2 into f(x) , f(2)=0
f(x)=(x+1)(x-2)(x^2+x-12)
=(x+1)(x-2)(x+4)(x-3)=0

so x=-1,2,-4 or 3