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If for an A.P., a_1+a_3+a_5+a_8+a_{10}+a_{12}=12, then find  the value of a_{1}+a_{12}


 

Option: 1

2


Option: 2

4


Option: 3

6


Option: 4

0


Answers (1)

best_answer

Using the property that sum of terms equidistant from start and end of an AP is equal to sum of first and last terms.

As there are 12 terms in given A.P., so

a_2+a_{10}=a_1+a_{12}            (a_{10} \: is\: 3^{rd }\text{ term from end })

a_5+a_8=a_1+a_{12}              (a_{8} \: is\: 5^{th }\text{ term from end })

So

a_1+a_3+a_5+a_8+a_{10}+a_{12}=12

\Rightarrow 3(a_1+a_{12})=12

\Rightarrow a_1+a_{12}=4

Posted by

Ritika Kankaria

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