乘法公式：(a+b+c)²=a²+b²+c²+2ab+2bc+2ac
(x±y)²=x²±2xy+y²
(x+y)(x-y)=x²-y²
1.(1+2x+x²)²
=1+4x²+x^4+4x+4x^3+2x²
=x^4+4x^3+4x²+2x²+4x+1
=x^4+4x^3+6x²+4x+1
2.(x+y-z)²
=x²+y²+z²+2xy-2yx-2xz
3.(6ab-4a²-9b²)²(2a+3b)²
=-(4a²-6ab+9b²)²(2a+3b)²
=-[(2a-3b)²]²(2a+3b)²
=-(2a-3b)²(2a-3b)²(2a+3b)²
=(3b-2a)²(2a-3b)²(2a+3b)²
=(3b-2a)²(4a²-9b²)²
=