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प्रश्न
Find the sum of first 'n' even natural numbers.
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उत्तर
First n even natural numbers are 2, 4, 6, 8, ....... 2n
t1 = first term = 2
tn = last term = 2n
Sn = `"n"/2["t"_1 + "t"_"n"]` ......[Formula]
= `"n"/2 [2 + 2"n"]`
= `"n"/2 xx 2(1 + "n")`
= `"n"(1 + "n")`
∴ m of first n even natural numbers is n(1 + n).
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