x^2(3x+5y)^2-y^2(5x+3y)^2 逆用积的乘方=[x(3x+5y)]^2-[y(5x+3y)]^2 用平方差=[x(3x+5y)+y(5x+3y)][x(3x+5y)-y(5x+3y)]=(3x^2+5xy+5xy+3y^2)(3x^2+5xy-5xy-3y^2)=(3x^2+10xy+3y^2)(3x^2-3y^2)提取公因式3=3(3x^2+10...