find the sum of following 7+14+21.....to 20 terms
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Hey !!!
Given :- First term = 7
second term = 14
common difference= a₂ -a₁ = 14 -7 = 7
∵ sum of nth term = n/2 {2a + ( n - 1 ) d
hence,
=> 20/2 ( 2* 7 + ( 20 - 7 )7
=> 10 ( 14 + 13* 7)
=> 10 ( 14 + 91 )
=> 10 *105
=> 1050 Answer
_________________________
Hope it helps you !!!
@Rajukumar111
Given :- First term = 7
second term = 14
common difference= a₂ -a₁ = 14 -7 = 7
∵ sum of nth term = n/2 {2a + ( n - 1 ) d
hence,
=> 20/2 ( 2* 7 + ( 20 - 7 )7
=> 10 ( 14 + 13* 7)
=> 10 ( 14 + 91 )
=> 10 *105
=> 1050 Answer
_________________________
Hope it helps you !!!
@Rajukumar111
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