数学高手来（分解因式）

1.4x^3-31+15 不对吧
是不是4x^3-31x+15？
如果是则
4x^3-31x+15
=4x^3-36x+5x+15
=4x(x^2-9)+5(x+3)
=4x(x+3)(x-3)+5(x+3)
=(x+3)(4x^2-12x+5)
=(x+3)(2x-5)(2x-1)

2.2a^2b^2+2a^2c^2+2b^2c^2-a^4-b^4-c^4
=-[(a^2-b^2+c^2)^2-4a^2c^2]
=-(a^2-b^2+c^2+2ac)(a^2-b^2+c^2-2ac)
=-[(a+c)^2-b^2][(a-c)^2-b^2]
=-(a+c+b)(a+c-b)(a-c+b)(a-c-b)

3.x^2-2x-2y^2+4y-xy
=(x-2y)(x+y)-2(x-2y)
=(x-2y)(x+y-2)

4.x^3+5x^2+3x-9
=x^3-x^2+6x^2+3x-9
=x^2(x-1)+3(x-1)(2x+3)
=(x-1)(x^2+6x+9)
=(x-1)(x+3)^2

5.x^4+2x^3-9x^2-2x+8
=x^4-x^3+3x^3-3x^2-6x^2-2x+8
=x^3(x-1)+3x^2(x-1)-2(x-1)(3x+4)
=(x-1)(x^3+3x^2-6x-8)
=(x-1)[(x-2)(x^2+2x+4)+3x(x-2)]
=(x-1)(x-2)(x^2+5x+4)
=(x-1)(x-2)(x+1)(x+4)

都是简单的