Giải thích các bước giải:
$B=\dfrac{1}{3x^2y+xy^2-xy}+\dfrac{1}{2xy^2-5xy}-\dfrac{1}{3x^2y}$
$\to B=\dfrac{1}{xy\left(3x+y-1\right)}+\dfrac{1}{xy\left(2y-5\right)}-\dfrac{1}{3x^2y}$
$\to B=\dfrac{3x\left(2y-5\right)}{3x^2y\left(2y-5\right)\left(3x+y-1\right)}+\dfrac{3x\left(3x+y-1\right)}{3x^2y\left(2y-5\right)\left(3x+y-1\right)}-\dfrac{\left(2y-5\right)\left(3x+y-1\right)}{3x^2y\left(2y-5\right)\left(3x+y-1\right)}$
$\to B=\dfrac{3x\left(2y-5\right)+3x\left(3x+y-1\right)-\left(2y-5\right)\left(3x+y-1\right)}{3x^2y\left(2y-5\right)\left(3x+y-1\right)}$
$\to B=\dfrac{9x^2+3xy-3x-2y^2+7y-5}{3x^2y\left(2y-5\right)\left(3x+y-1\right)}$