九道关于平方差和完全平方的数学题~
1.4x³-6x²-2x2.a(x-3)³-b(y-x)²3.9m²-n平方4.25x²-十六分之一y²5.(x²-y²)²-4x²y²6.(xy)²-4xy+47.m的四次方-2m²+18.(x+y)²+18(x+y)+819.(x²+2x²)+2(x²+2x)+1选几道也行啊!