JEE Main 2026 Mathematics question
If f : ℕ → ℤ is defined by , k∈ℕ, and , then k is equal to:
Answer: (A)
Solution
Expanding the determinant and summing over n=1 to k gives 7k(2k²+3k+1)/6=98, whose only real solution is k=3.
If f : ℕ → ℤ is defined by , k∈ℕ, and , then k is equal to:
Expanding the determinant and summing over n=1 to k gives 7k(2k²+3k+1)/6=98, whose only real solution is k=3.