(1)分解因式 (x+2y)^2-(x-y)^2 =(x+2y+x-y)(x+2y-x+y)=3y(2x+y)(2)利用分解因式计算 (181^2-61^2)/(301^2-181^2) (181+61)(181-61)/(301-181)(301+181)=242×120/120×482=121/241