Rút gọn :
b ) \(\frac{x^2+3xy+2y^2}{x^2+2x^2y-xy^2-2y^2}\)
\(=\frac{x^2+xy+2xy+2y^2}{x^3-xy^2+2x^2y-2y^3}\)
\(=\frac{x\left(x+4\right)+2y\left(x+y\right)}{x\left(x^2-y^2\right)+2y\left(x^2-y^2\right)}\)
\(=\frac{\left(x+y\right)\left(x+2y\right)}{\left(x^2-y^2\right)\left(x+2y\right)}\)
\(=\frac{\left(x+y\right)\left(x+2y\right)}{\left(x-y\right)\left(x+y\right)\left(x+2y\right)}\)
\(=\frac{1}{x-y}\)