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12+12+22+12+22+32+ upto 22nd terms is 

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a
23276
b
22736
c
22738
d
227152

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detailed solution

Correct option is A

tr=12+22+…+r2=16r(r+1)(2r+1)=162r3+3r2+r∴∑r=1n tr=13⋅14n2(n+1)2+12⋅16n(n+1)(2n+1)+112n(n+1)=112n(n+1)n2+n+2n+1+1=112n(n+1)n2+3n+2=112n(n+1)2(n+2)∴∑r=122 tr=112(22)(23)2(24)=23276


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Let m be a positive integer, then S=k=1mk1k+1k+1+1k+2++1m is equal to :


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