25(x-2y)平方-4(2y+x)平方
问题描述：
25(x-2y)平方-4(2y+x)平方
答
=[5(x-2y)]²-[2(x+2y)]²
=(5x-10y+2x+4y)(5x-10y-2x-4y)
=(7x-6y)(3x-14y)再问你个题呗，简便方法计算73×145²-105²×73=73×(145²-105²)=73×(145+105)(145-105)=73×250×40=730000