bai1:tinh tong S=1.3+3.5+5.7+...+99.101
bai2 :tinh tong S=1.4+4.7+7.10+...+2017.2020
bai 3: tinh tong N=2.4+4.6+6.8+..+100.102
bai 4: tinh tóng=2.6+6.10+10.14+14.18+...+42.46+50.54
bai 5:tinh tongB=2^2+4^2+6^2+...+100^2
bai 6:C=1^2+3^2+...+100^2
bai7: biet 1^2+2^2+3^2+...+10^2=385 tinh tong 2^2+4^2+6^2+...+20^2
bai 8: tinh tong s=1^2+2^2+3^2+...+99^2
Tinh tong S=1/1×2+1/2×3+1/3×4+...+1/2014×2015+1/2015×2016
Tinh tong S=1/1×2+1/2×3+1/3×4+...+1/2014×2015+1/2015×2016
tinh tong S=1+4+4^2+4^3+...+4^100
Tinh tong S = 1×2+2×3+3×4+4×5+•••••+99×100
Tinh tong;S=1-2+3-4+...+999-1000
tinh tong
a)s=1+(-2)+3+(-4)+.......+2009+(-2010)
b)s=1+(-2)+(-3)+4+5+6(-6)+(-7)+......+2008+2009+(-2010)
tinh tong sau = 2 cach s= 1+ (-2) +3 +(-4) + ......+(-98) + 99
tinh tong :S=1-2+3-4+5-6+...+2015-2016
