(1)2a/5a²b+3b/10ab²
=2/(5ab)+3/(10ab)前项约a;后项约b;
=4/(10ab)+3/(10ab)通分
=7/(10ab)合并
(2)3y/2x+2y+2xy/x²+xy
=3y/(2x+2y)+2xy/[x(x+y)]估计你原题是代括号的
=3y/[2(x+y)]+2xy/[x(x+y)]前项分母提取公因数2;后项分母提取公因数x;
=3y/[2(x+y)]+4y/[2(x+y)]前项不变照写;后项分子分母同约x,同时后项分母配2;
=(3y+4y)/[2(x+y)]上面前后项已经通分,合并
=7y/[2(x+y)]继续合并分子
(3)2x/x²-64y²-1/x-8y
=2x/(x²-64y²)-1/(x-8y)估计你原题是代括号的
=2x/[(x-8y)(x+8y)]-1/(x-8y)用到平方差公式:a^2-b^2=(a-b)(a+b)
=2x/[(x-8y)(x+8y)]-(x+8y)/([(x-8y)(x+8y)]通分使前后两项分母相同,准备合并
=[2x-(x+8y)]/[(x-8y)(x+8y)]合并前后两项
=[2x-x-8y]/[(x-8y)(x+8y)]注意:a-(b+c)=a-b-c,而不是=a-b+c
=[x-8y]/[(x-8y)(x+8y)]约分化简
=1/(x+8y)Gameover!§※
补充一条:分数的分母是不能为零滴,虽然这几个题目没涉及到.