SOLUTION: a series has first term 7 and 5th term 23. find the common difference , 15th term and sum of the first 10 terms.
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Question 1079599: a series has first term 7 and 5th term 23. find the common difference , 15th term and sum of the first 10 terms. Answer by amfagge92(93) (Show Source):
You can put this solution on YOUR website! a=7 5th term=23
⇒T5th=7+4d=23
7+4d=23
4d=16
d=4
⇒common difference=4
15th term=a+14d
7+(14*4)=63
⇒15th term=63
Sum of 10th term
=n/2{2a+(n-1)d}
10/2{2*7+(9*4)}
=250
