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प्रश्न
In an A.P. a = 2 and d = 3, then find S12
उत्तर
a = 2 and d = 3 ......[Given]
Since Sn = `"n"/2 [2"a" + ("n" - 1)"d"]`,
S12 = `12/2 [2(2) + (12 - 1)(3)]`
= 6[4 + 11(3)]
= 6(4 + 33)
= 6(37)
= 222
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