Question

(x-y by 3 +1)(x-y by 3 - 1)

Answer 1

$= \frac{x - y}{3 + 1} \times \frac{x - y}{3 - 1} \\ = \frac{x - y}{4} \times \frac{x - y}{2} \\ = \frac{ {x}^{2} - 2xy + {y}^{2} }{8}$