NDA 1 2025 Maths, question 4

Solution.

Answer: (a) 0

1. The denominators imply $x,y \neq 0$.
2. Multiplying the first equation by $y$ and the second by $x$ gives $xy + 5 = 4y$ and $xy + 5 = - 4x$.
3. Consequently $4y = - 4x$, so $x + y = 0$.