Question

In the arithmetic sequence 6,11,16. find
* Sum of 15 terms​

Answer 1

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given

• AP - 6,11,16
• a-6
• common difference is a2-a1=11-6=5 or a3-a2= 16-11=5

To find

• sum of 15 terms

solution

formula to find sum

s(n)=n/2(2a+(n-1)*d)

=15/2(2*6+(15-1)*5)

=15/2(12+70)

=15/2(82)

=15*41

=615

Thanks

Hope its helpful

by gavya