Asked by ISOSMEXY
the sum of the first n terms of an arithmetic series is Sn=2n^2+5n.
Determine the first 3 terms. Help!!!
Determine the first 3 terms. Help!!!
Answers
Answered by
Reiny
S1 would be the first term
S1 = 2+5 = 7 , so a = 7
S2 = 2(4) + 10 = 18
S2 = a + a+d = 18
14+d = 18
d = 4
the sequence is: 7, 11, 15, ...
check:
sum3 by formula = 2(9) + 15 = 33
by just adding the 3 terms
= 7+11+15 = 33
All seems good
S1 = 2+5 = 7 , so a = 7
S2 = 2(4) + 10 = 18
S2 = a + a+d = 18
14+d = 18
d = 4
the sequence is: 7, 11, 15, ...
check:
sum3 by formula = 2(9) + 15 = 33
by just adding the 3 terms
= 7+11+15 = 33
All seems good
Answered by
Mutshidzi
I need help for proving the n term
Answered by
Jessi
how about calculate the S8?
Answered by
Dan
From which textbook is this question from?
Can you tell me the author please
Can you tell me the author please
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