25(x2+ 2xy +y2)-9(x2-2xy+y2)因式分解.x2,y2是x平方,y平方的意思.2xy就是2xy.快,

题目

25(x2+ 2xy +y2)-9(x2-2xy+y2)因式分解.x2,y2是x平方,y平方的意思.2xy就是2xy.快,

答案

25(x²+ 2xy +y²)-9(x²-2xy+y²)
=[5(x+y)]²-[3(x-y)]²
=[5(x+y)+3(x-y)][5(x+y)-3(x-y)]
=(8x+2y)(2x+8y)
=4(4x+y)(x+4y)