姿色撩人
幼苗
共回答了21个问题采纳率:95.2% 举报
(1)3x^4-12x^2
=3x²(x²-4)
=3x²(x-2)(x+2)
(2)9(x-y)^2-4(x+y)^2
=[3(x-y)-2(x+y)][3(x-y)+2(x+y)]
=(3x-3y-2x-2y)(3x-3y+2x+2y)
=(x-5y)(5x-y)
(3)(3a+b)(a-2b)-2a(2b-a)
=(a-2b)(3a+b+2a)
=(a-2b)(5a+b)
(4)-12x^3+15x^2y-x
=-x(12x²+15xy-1)
1年前
2