S= 4+10+18
S=14+18
=32
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cho mk
S = 1 x 4 + 2 x 5 + 3 x 6
S = 4 + 10 + 18
S = 14 + 18
S = 32
A1/2+1/3+1/4+1/5+......+1/2015+1/2016
a,ting tong
b,neu cachbo 1 p/s nhung van bang A
cho phan so co tong bang -3 va tich bang 12/5 ting tong nghich dao cua 2 phan so do?
tinh tong
a)s=1+(-2)+3+(-4)+.......+2009+(-2010)
b)s=1+(-2)+(-3)+4+5+6(-6)+(-7)+......+2008+2009+(-2010)
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=1-2+3-4+5-6+...+2015-2016
TINH TONG:
S=1+2-3-4+5+6-7-8+....-2005-2006+2007+2008
Tinh tong S = 1×2+2×3+3×4+4×5+•••••+99×100
Cho S = 1 + 3^2 + 3^4 + 3^6 + ... + 3^98. Tinh tong S va chung minh S chia het cho 10
chung to tong: S=51+52+53+54+...+599+5100 chia hết cho 6
