Question

Write the following arithmetic series in summation notation.
7+9+11+ . . . +35
..

Answer 1

`S_(n)=315`

Explanation:

`a_(1)=7\\a_(2)=9\\a_(n)=35\\`

d=9-7=2

no of terms n,

`n=\frac{a_{n-a_(1)} }{d} +1`

`n=\frac{{35}-{7}}{2} +1`

`n=15`

sum of series,

`S_(n)=(n)/(2) (a_(1)+a_(n))\\\\S_(n)=(15)/(2) (7+35})\\\\S_(n)=315`