a)[tex]= \frac{ x^{2} }{xy} [/tex]
b)[tex]= \frac{ y^{2} }{y(x-1)}= \frac{ y^{2} }{xy-y} [/tex]
c)[tex] \frac{a b^{2} }{b(2+a)} = \frac{a b^{2} }{2b+ab} [/tex]
d)[tex] \frac{(x-1 )^{2} }{(x+1)(x-1)}= \frac{(x-1)^{2} }{ x^{2} -1}= \frac{ x^{2} -2x+1}{ x^{2} -1} [/tex]
