JEE MainMathematicsSequences and SeriesNumerical+4 / −1
The roots of the quadratic equation are and terms of an arithmetic progression with common difference . If the sum of the first 11 terms of this arithmetic progression is 88 , then is equal to .
Numerical answer
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Correct answer: 474
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Let the arithmetic progression have first term and common difference .
Then the -th term is
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Write the 10th and 11th terms.
These are the roots of
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Use the sum of first 11 terms.
Given
Since ,
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Find the two roots explicitly.
So the roots are and .
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Use Vieta's formulas for .
For a quadratic :
- sum of roots
- product of roots
Here,
So,
Now, hence
Also, hence
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Compute .
Therefore,
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