Question

Answer 1

a: \(=\dfrac{\left(x-y\right)\left(x+y\right)}{x^2+y^2}\cdot\dfrac{\left(x-y\right)\left(x+y\right)}{\left(x-y\right)^2}=\dfrac{\left(x+y\right)^2}{x^2+y^2}\)

b: \(=\dfrac{x^2-xy+y^2}{\left(x-y\right)\left(x+y\right)}\cdot\dfrac{\left(x-y\right)^2}{\left(x+y\right)\left(x^2-xy+y^2\right)}=\dfrac{x-y}{\left(x+y\right)^2}\)

c: \(=y\left(x+y-1\right)\cdot\dfrac{\left(x-y\right)}{x\left(x+y-1\right)}=\dfrac{y\left(x-y\right)}{x}\)