如果x^2+px+8=(x-2)(x-4)那么p=?因式分解:(x-1)(x+4)-6x^2+5/6+1/6

Question

如果x^2+px+8=(x-2)(x-4)那么p=?
因式分解:
(x-1)(x+4)-6
x^2+5/6+1/6

Answer 1

(x-2)(x-4)=x^2-6x+8
比较左边与右边,得p=-6
(x-1)(x+4)-6
=x^2+3x-4-6
=x^2+3x-10
=(x-2)(x+5)
x^2+5/6+1/6
=(x+1/3)(x+1/2)