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The nth term of an ap is 2n + 1 then the sum of n terms of an ap is |
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Answer» n(n+2) An= 2n+1If n=1, than A1(first term of AP)= 2×1+1=3A2= 2×2+1= 5From A1 and A2 we can get common difference=5-3=2Sum of n terms =(n/2)[2a+(n-1)d]=(n/2)[2×3+(n-1)2]=(n/2)[6+2n-2]=(n/2)[4+2n]=(n/2)×2[2+n]=n(2+n)=n^2+2n |
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