Find the sum of all odd natural number form 20 to 60.
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Answered by
0
Answer:
required sum=(23+29+31+.... +59)
Tn=59
a=23
d=6
Tn=a+(n-1) d
23+(n-1) ×6=59
23+6n-6=59
17+6n=59
6n=42
n=7
Sn=n/2(a+l)
=7/2(23+59)
=7/2×82
=294
Explanation:
hope it helps
Answered by
0
answer is 800
21+23+25+59 =
n/2x(a+l) =20/2(21+59)= 10x80=800
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