1...3a^2(x-y)-27(x-y)b^2
问题描述：
1...3a^2(x-y)-27(x-y)b^2
2...-4a^3 b^4+16a^2 b^5-16ab^6
3...a^2-(b^2+c^2-2bc)
4...(x+2)(x+4)+x^2-4
5.9m^2-6m+2n-n^2
答
3(x-y)(a-3b)(a+3b),-4ab^4(a-2b)^2,(a-b+c)(a+b-c),2(x+2)(x+1)这几个都很一般就不写步骤了。
最后这个要拆添个常数项稍微麻烦点。。=9m^2-6m-3+3+2n-n^2=3(m-1)(3m+1)-(n-3)(n+1)