???????????????? given ?????????????... did yu tri tu make that + - + - + - ??????????????... such as 1-2^2 +3^2 -4^2 +5^2 -6^2...tu 100?????... 1^2 -2^2=1-4=-3... 3^2-4^2=9-16=-7... 5^2 -6^2=25-36=-11... 99^2 -100^2=9801-1000=-199... yu hav negativ av sequens...3+7+11+...+199... (50 terms)... averaej=(3+199)/2=202/2=101... sum=num*averaej=50*101=5050... anser=-5050