find the 60th term of the AP 8,10,12,if it has a total of 60 terms and hence find the sum of its last ten terms?
Answers
Answered by
4
a. = 8
d = 2
a60 = a + 59d
= 126
S10 = S60 - S50
= 4020 - 2850
= 2170
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d = 2
a60 = a + 59d
= 126
S10 = S60 - S50
= 4020 - 2850
= 2170
if it helpful please rate it brainliest
Answered by
40
Answer:
Step-by-step explanation:
Solution :-
Here,
First term, a = 8,
Common difference, d = 10 - 8 = 2
We know that,
a(n) = a + (n - 1)d
Then, a(60) = 8 + (60 - 1)2
a(60) = 8 + 59 × 2
a(60) = 126.
and, a(51) = 8 + (51 - 1)2
a(51) = 8 + 50 × 2
a(51) = 8 + 100
a(51) = 108
Sum of last terms = a(51) + a(52) + ..... + a(60).
Here,
a = 108 and d = 2.
⇒ S(10) = 10/2[2 × 108 + (10 - 1)2]
⇒ S(10) = 2[216 + 18
⇒ S(10) = 5 × 234
⇒ S(10) = 1170
Hence, the sum of last 10 terms is 1170.
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