Answer:
[tex](y - 1)(x + y + 1)[/tex]
Step-by-step explanation:
[tex]y(x + y) - 1(1 + x)[/tex]
Lets expand it.
[tex] = > xy + {y}^{2} - x - 1[/tex]
Lets re-arrange it.
[tex] = > xy - x + {y}^{2} - 1[/tex]
Lets split [tex] {y}^{2} - 1[/tex]
So,
[tex] = > x(y - 1) + (y + 1)(y - 1)[/tex]
[tex] = > (y - 1)(x + y + 1)[/tex]
