pls help me pls please
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Important concept:Sum of sqaure of first n natural no. =n(n+1)(2n+1)/6
of sqaure of first n natural no. =n(n+1)(2n+1)/6sum of first n natural number=n(n+1)/2
Now, let's move on question
Applying the above formula we get
n(n+1)(2n+1)/{2(n)(n+1)/2}=17
2n+1=17
n=8
now,
required sum S=(2×1-1)+(2×2-1)+(2×3-1)+......+(2×8-1)
S=1+3+5+.....+15
this is now in AP
so,apply the sum formula of AP
=n/2 ×(a+l)=4×(1+15)=64
Hence,the required sum is 64