(1/a+1/b)²/(1/a²-1/b²)等于几

问题描述:

(1/a+1/b)²/(1/a²-1/b²)等于几

(a+b)/(b-a)x²/2y²*x/2y²等于多少?x³/4y^4分子与分子,分母与分母相乘的啊