2/(1-a)+1/(a-1)²
=-2(a-1)/(a-1)²+1/(a-1)²
=[1-2(a-1)]/(a-1)²
=(3-2a)/(a-1)²
如果不懂,请Hi我,祝学习愉快!再问你一个问题：计算：x—4y分之3x+4y—x分之x+y—x—4y分之7x