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Mathematics - Sequence & Series Question with Solution | TestHub

MathematicsSequence & SeriesA.P.Easy2 minPYQ_2016

MathematicsEasystatement

Let $a_{1}, a_{2}, a_{3}, \dots a_{n}, \dots$ ,be in A.P. If $a_{3} + a_{7} + a_{11} + a_{15} = 72$ , then the sum of its first $17$ terms is equal to :

Options:

Answer:

A

Solution:

$a_{3} + a_{7} + a_{11} + a_{15} = 72$

$(a_{3} + a_{15}) + (a_{7} + a_{11}) = 72$

$a_{3} + a_{15} = a_{7} + a_{11} = a_{1} + a_{17}$

$a_{1} + a_{17} = 36$

$S_{17} = \frac{17}{2} (a_{1} + a_{17}) = 17 \times 18 = 306$

Stream:JEESubject:MathematicsTopic:Sequence & SeriesSubtopic:A.P.

⏱ 2mℹ️ Source: PYQ_2016

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