(SSC स्नातक स्तरीय Tier-II परीक्षा,...
Question
Fullscreen

(SSC स्नातक स्तरीय Tier-II परीक्षा, 04.09.2011) 14, 11+ 12+...+21' का योग = ? (1) 2926 (2) 3017 (3) 3215 (4) 3311 (SSC संयुक्त स्नातक स्तर Tier-। परीक्षा, 16.09.2012)

11th - 12th Class
Maths
Solution
149
Rating
4.0 (1 ratings)
Fullscreen
14. ( (1) 1^{2}+2^{2}+3^{2}+ldots ldots ldots+n^{2} ) ( quad=frac{n(n+1)(2 n+1)}{6} ) ( therefore 11^{2}+12^{2}+ldots+21^{2} ) ( =left(1^{2}+2^{2}+3^{2}+ldots+21^{2}right)- ) ( =frac{21(21+1)(42+1)}{6}-frac{10 times 11 times 21}{6} ) ( =frac{21 times 22 times 43}{6}-frac{10 times 11 times 21}{6} ) ( =3311-385=2926 )
Quick and Stepwise Solutions Just click and Send Download App OVER 20 LAKH QUESTIONS ANSWERED Download App for Free