NDA Mathematics Question (2025) — Solution

Step-by-step solution

Given f(xy) = f(x+y) for all real values of x and y. Substituting y = 0, we get f(x 0) = f(x + 0), which simplifies to f(0) = f(x) for all real x. This implies that f(x) is a constant function for all real values of x. Since f(5) = 10, the constant value of the function is 10. Thus, f(x) = 10 for all x R . We need to find the value of f(20) + f(-20). f(20) = 10 f(-20) = 10 f(20) + f(-20) = 10 + 10 = 20 Answer: 20