10x²+30x+20约分 怎么会变成10(x+1)(x+2) x³+2x²-x-2约分怎么变成(x+2)(x+1) (x-1)把过程写清楚些
问题描述:
10x²+30x+20约分 怎么会变成10(x+1)(x+2) x³+2x²-x-2约分怎么变成(x+2)(x+1) (x-1)
把过程写清楚些
答
10x^2+30x+20
=10(x^2+3x+2)
=10(x+1)(x+2)
x^3+2x^2-x-2
=x^2(x+2)-(x+2)
=(x+2)(x^2-1)
=(x+2)(x+1)(x-1)