find sum of first 40 terms of series 1^2-2^2+3^2-4^2+....

• Ans: -820
  
  1^2-2^2+3^2-4^2+...+n^2= - n*(n+1)/2 (If n is Even)
  1^2-2^2+3^2-4^2+...+n^2= n*(n+1)/2 (If n is Odd)
  
  So Sum= - (40/2)(40+1)= -820
• 8 years agoHelpfull: Yes(5) No(0)