-4a^3+16a^2b-26ab^2 x^5-x^3 (x^2+y^2)^2-4x^2y^2 25(x+y)^2+10(x+y)+1 a*(-a^2)^3*(a^3)^2

-4a^3+16a^2b-26ab^2
=-2a(2a^2-8ab+13b^2)
x^5-x^3
=x^3(x^2-1)
=x^3(x-1)(x+1)
(x^2+y^2)^2-4x^2y^2
=(x^2+y^2+2xy)(x^2+y^2-2xy)
=(x+y)^2(x-y)^2
25(x+y)^2+10(x+y)+1
=[5(x+y)+1]^2
=(5x+5y+1)^2
a*(-a^2)^3*(a^3)^2
= a*(-a^6)*(a^6)
=-a^13-2a(2a^2-8ab+13b^2) tangram_guid_1360583159324???????? 为什么不能提一个-4a呢？-4a^3+16a^2b-26ab^2=-4a(a^2-4ab+13/2b^2)(有分数，一般不这样提取公因式）