Find the sum of first 20 terms
of arithmetic series 5 + 10+15
using Suitable formula
Answers
Answered by
65
Answer:
we know that a=5 and d=5 and s20=?
so sn=n/2{2a+(n-1) d}
s20=20/2{2×5+(20-1) 5}
s20=10{10+(19) 5}
s20=10{10+95}
s20=10(105)
s20=1050
Answered by
3
Concept:
Sum of AP:
S = n / 2 [ 2 a + (n − 1) × d]
Given:
We are given the arithmetic series:
5 + 10 + 15 ...
Find:
We need to find the sum of its first 20 terms.
Solution:
The formula is:
S = n / 2 [ 2 a + (n − 1) × d]
n = 20
a = 5
d = 5
Putting it in the formula, we get that:
S = 20 / 2 [ 2(5) + (20 - 1) × 5]
S = 10 [ 10 +19 × 5]
S = 10 [ 10 + 95]
S = 10 [ 105]
S = 1050
Therefore, we get the sum of the first 20 terms as 1050.
#SPJ2
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