JEE MainMathematicsSequences and SeriesNumerical+4 / −1
Let be an Arithmetic Progression such that . Then is equal to .
Numerical answer
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Correct answer: 11132
Let the A.P. be We are given
We need to find
1. Write the given sum in terms of and
The terms inside the bracket are These are terms whose indices are multiples of from to .
Number of such terms:
Now,
So,
Hence,
Now, Also, Therefore,
Thus,
Also,
So the given condition becomes that is, 406a_1+410669d=2233. \tag{1}
2. Express
Sum of first terms of an A.P. is
So we need .
3. Relate equation (1) to
Observe that Also, Hence,
From (1), So,
4. Compute the required sum
Therefore,
5. Final answer
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