if the nth term of a sequence is 5+2n ,the sum to first 20 terms is
Answers
Answered by
1
Answer:
Answer:S20=520
S30=1080
Step-by-step explanation:
Tn=5+2n
T1=a=5+2 (1)=5+2=7
T2=5+2 (2)=5+4=9
Common difference =T2-T1=9-7=2
Sn=n/2 (2a+(n-1)d)
S20=20/2 (2 (7)+(20-1)2) = 10 (14+19 (2)) =10 (14+38) = 10 (52) =520//
S30=30/2 (2 (7)+(30-1)2) = 15 (14+29 (2)) = 15 (14+58) = 15 (72) = 1080//
Answered by
0
Answer:
Step-by-step explanation:
Attachments:
Similar questions