分类：教育/科学-理工学科-数学
问题：因式分解(x+y)^2
要过程
回答：(x+y)^2-4(x-y)^2-4(x^2-y^2) 
=(x+y-2x+2y)(x+y+2x-2y)-4(x^2-y^2)
=(3y-x)(3x-y)-4(x^2-y^2)
=9xy-3x^2-3y^2+xy-4x^2+4y^2
=y^2+10xy-7x^2

=[y+(-5+4√2)x][y+(-5-4√2)x]