find the sum of the first 25 trrms of the series 5.6+6.7+7.8+.....

find the sum of the first 25 trrms of the series 5.6+6.7+7.8+.....

we have ,

5.6 + 6.7 + 7.8 + 8.9 +…………upto 25 terms

We have first term (a) = 5.6

common Difference = 6.7 – 5.6 = 1.1

= 7.8 – 6.7 = 1.1

= 8.9 – 8.9 = 1.1

This series is in arithmetic progression ,

So ,we have the formula for sum

sum =

on putting the values , we get

=

=

=

=

= 25*18.8

= 470 ans

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