a. \(\dfrac{x^2-y^2+3x-3y}{x^2y-xy^2-x+y}\)
= \(\dfrac{\left(x^2-y^2\right)+\left(3x-3y\right)}{\left(x^2y-xy^2\right)-\left(x-y\right)}\)
= \(\dfrac{\left(x-y\right)\left(x+y\right)+3\left(x-y\right)}{xy\left(x-y\right)-\left(x-y\right)}\)
= \(\dfrac{\left(x+y+3\right)\left(x-y\right)}{\left(xy-1\right)\left(x-y\right)}\)
= \(\dfrac{x+y+3}{xy-1}\)
b. \(\dfrac{x^2+x-2}{x^2+7x+10}\)
= \(\dfrac{x^2+2x-x-2}{x^2+5x+2x+10}\)
= \(\dfrac{\left(x^2+2x\right)-\left(x+2\right)}{\left(x^2+5x\right)+\left(2x+10\right)}\)
= \(\dfrac{x\left(x+2\right)-\left(x+2\right)}{x\left(x+5\right)+2\left(x+5\right)}\)
= \(\dfrac{\left(x-1\right)\left(x+2\right)}{\left(x+2\right)\left(x+5\right)}\)
= \(\dfrac{x-1}{x+5}\)
