（a+b）的平方+6（a+b）+9 分解因式

(a+b)^2+6(a+b)+9
=[(a+b)+3]^2
=(a+b+3)^2
a^2-2a(b+c)+(b+c)^2
=[a-(b+c)]^2
=(a-b-c)^2
-a+2a^2-a^3
-a(a^2-2a+1)
=-a(a-1)^2
16a^2b-16a^3-4ab^2
=4a(4ab-4a^2-b^2)
=-4a(4a^2-4ab+b^2)
=-4a(2a-b)^2
a^4-1
=(a^2+1)(a^2-1)
=(a^2+1)(a+1)(a-1)
x^4y^4-8x^2y^2+16
=(x^2y^2-4)^2
=(xy+2)^2(xy-2)^2