题目内容
(x+y)(x-y)2-(x-y)(x2-y2)
||-|4.2|+|-|
()5÷()-4÷(-)-3
++
[(-a5)2]3÷[(-a)3]5·(-a)
(2x-3y)2-(4y-3x)(3x+4y)
(-y4n-1÷y2n+1-y3n+2÷yn-1)÷(-yn-1)
[15-(1÷1+1÷3)]÷(-1)
(-0.5)-(-3)+2.75-(+7).