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प्रश्न
Find the sum of first 10 terms of the A.P.
4 + 6 + 8 + .............
उत्तर
Here,
First term, a = 4
Common difference, d = 6 – 4 = 2
n = 10
`S = n/2 [2a + (n - 1)d]`
= `10/2 [2(4) + 9(2)]`
= 5[8 + 18]
= 5 × 26
= 130
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