Question

(px - y)² = P² -2y/x*p+1​

Answer 1

1. expand LHS=  p^2 X^2 + y^2-2pxy

2. divide LHS by x = P^2 X- 2py+y^2 / X

then divide by p+1 = p^2-2y/x*p+1

hence, LHS=RHS.