b: \(\left(xy-8\right)^2-1\)
\(=\left(xy-8\right)^2-1^2\)
\(=\left(xy-8-1\right)\left(xy-8+1\right)\)
=(xy-7)(xy-9)
a: \(xy+y^2-x-y\)
\(=y\left(x+y\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(y-1\right)\)
2 a, xy + y^2 - x - y
= (xy + y^2 ) - (x + y)
= y( x + y ) - ( x + y )
= ( x + y ) ( y - 1 )