(x-2y)²(x+2y)²=[(x-2y)(x+2y)]²=(x²-4y²)²=x的4次方-8x²y²+y的4次方(a-2b+3)(a+2b-3)=[a-(2b-3)][a+(2b-3)]=a²-(2b-3)²=a²-4b²+12b-9很高兴为您解答,...