Question

(xy+1)2−(x+y)2

Answer 1

\(\left(xy+1\right)^2-\left(x+y\right)^2\\ =\left(xy+1-x-y\right)\left(xy+1+x+y\right)\\ \)

Answer 2

\(\left(xy+1\right)^2-\left(x+y\right)^2\)

\(=\left(xy+1-x-y\right)\left(xy+1+x+y\right)\)

\(=\left[x\left(y-1\right)-\left(y-1\right)\right]\left[x\left(y+1\right)+\left(y+1\right)\right]\)

\(=\left(y-1\right)\left(x-1\right)\left(y+1\right)\left(x+1\right)\)