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
the sum of the first n terms of an arithmetic series is Sn=2n^2+5n.
Determine the first 3 terms. Help!!!
4 answers
I need help for proving the n term
how about calculate the S8?
From which textbook is this question from?
Can you tell me the author please
Can you tell me the author please
2 answers