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प्रश्न
An A.P. consists of 31 terms. If its 16th term is m, then the sum of all the terms of this A.P. is
विकल्प
16 m
62 m
31 m
`31/2` m
उत्तर
31 m
Explanation;
Hint:
t16 = m
S31 = `31/2` (2a + 30d)
= `31/2` (2(a + 15d))
...(∵ t16 = a + 15d)
= 31(t16) = 31m
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