JEE Main 2024 Mathematics question
Let Sₙ be the sum to n-terms of an arithmetic progression 3, 7, 11, ...... . If , then n equals .
Answer: 9
Solution
Sₖ = (k/2)[6 + (k − 1)4] = k(2k + 1) = 2k² + k. Then Σ Sₖ = 2n(n + 1)(2n + 1)/6 + n(n + 1)/2, so
See the full step-by-step solution
Create a free account to read the complete working, and practise questions like this in a timed test.
Create a free account