(x-1)(x+2)(x+3)(x+6)
=[(x-1)(x+6)][(x+2)(x+3)]
=(x^2+5x-6)(x^2+5x+5)
=(x^2+5x)^2-(x^2+5x)-30
=x^4+10x^3+25x^2-x^2-5x-30
=x^4+10x^3+24x^2-5x-30
(x-1)(x+2)(x+3)(x+6)怎么做?
(x-1)(x+2)(x+3)(x+6)
=[(x-1)(x+6)][(x+2)(x+3)]
=(x^2+5x-6)(x^2+5x+5)
=(x^2+5x)^2-(x^2+5x)-30
=x^4+10x^3+25x^2-x^2-5x-30
=x^4+10x^3+24x^2-5x-30