Tính theo cách hợp lý
a) (10^2+11^2+12^2):(13^2+14^2)
b)1.2.3....9 -1.2.3...8-1.2.3...7.8^2
c)(3.4.2^16)^2 /11.2^13.4^11-16^9
1.So Sánh
a) A=\(\dfrac{11}{2017}+\dfrac{4}{2019}và\) B=\(\dfrac{10}{2017}+\dfrac{10}{2019}\)
b) M=\(\dfrac{1}{5}+\dfrac{1}{12}+\dfrac{1}{13}+\dfrac{1}{14}+\dfrac{1}{30}+\dfrac{1}{61}+\dfrac{1}{62}và\dfrac{1}{2}\)
c) E=\(\dfrac{4116-14}{10290-35}và\) K=\(\dfrac{2929-101}{2.1919+404}\)
(3.4.2^16)^2/11.2^13.4^11-16^9
Không quy đồng hãy tính
B=5/2.1+4/1.11+3/11.2+1/1.15+13/15.4
Tính tổng
a)1+72+73+...+72016
b)1+42+43+...+42017
Chứng minh rằng
1414-1 chia hết 13
20152015-1 chia hết 2014
2) Tính B=\(\frac{5}{2.1}+\frac{4}{1.11}+\frac{3}{11.2}+\frac{1}{2.15}+\frac{13}{15.4}\)
Cho a=1/11+1/12=1/13+1/14+..+1/70
Cmr 4/3<A<2,5
Tính
a) A = 1 - 4 - 7 - 10 - .......- 2017
b) B = 2 - 6 - 10 -....... - 2018
c) C = 1 - 5 + 9 - 13+ 17- 21 + ......- 2017
cho S1=1+2 ; S2=3+4+5 ; S3=6+7+8+9 ; S4=10+11+12+13+14 .Tính S100
cho S1=1+2 ; S2=3+4+5 ; S3=6+7+8+9 ; S4=10+11+12+13+14. tính S100