Cho S = 1 + 3^2 + 3^4 + 3^6 + ... + 3^98. Tinh tong S va chung minh S chia het cho 10
Cho S=1+32+34+36+..................+398
tinh tong cua S va cmr S chia het cho 10
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
cho S= 1+3 mux2 +3 mũ 4 +3 mũ 6+.........+ 3 mũ 98. tinh tong Svà chứng minh Schia het cho 10
tinh tong s=1/2^2+1/3^2+...+ 1/10^2
tinh tong:
1/3+1/6+1/10+1/15+....+1/44
tinh tong cac so sau D=30+35+...+495+500
tinh tong :S=1-2+3-4+5-6+...+2015-2016
tinh tong
a)s=1+(-2)+3+(-4)+.......+2009+(-2010)
b)s=1+(-2)+(-3)+4+5+6(-6)+(-7)+......+2008+2009+(-2010)