Question

Find the sum of first 22 terms of an ap in whish d is 2 and 22nd term is 149

Answer 1

Dear student
Given d = 2,
22nd term = 149 ,
⇒ a+21d = 149
⇒a+21(2) = 149
⇒a+42 = 149
⇒a=149-42=107
Sn = (n/2)(2a+(n-1)d)
Sâ‚‚â‚‚ = (22/2)(2×107+(22-1)2)
Sâ‚‚â‚‚ = 11(214+21(2))
Sâ‚‚â‚‚ = 11(214+42)
Sâ‚‚â‚‚ = 11(256)
Sâ‚‚â‚‚ = 2816.


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