Các câu hỏi tương tự
Tinh nhanh :
A = ( 2016 + 2017 ) - ( 2017 + 2018 ) + ( 2018 - 16 )
B = ( 157 - 215 ) + ( 315 - 157 ) + ( 215 - 265 )
C = 1 . 3 - 2 . 4 + 3 . 5 + 4 . 6 + ..... + 7 . 9.- 8 . 10
Tính nhanh :C=1.3-2.4+3.5+4.6+....+7.9-8.10
S =1/1.3-1/2.4+1/3.5-1/4.6+1/5.7 - 1/6.8+1/7.9-1/8.10
Xem chi tiết
a. So sanh 2 phan so:A= 2015/2016+2016/2017+2017/2018 va B = 2015+2016+2017/2016+2017+2018
b.1/2.4+1/4.6+........+1/(2x-2).2x = 1/8
c.Cho A = 1/4+1/9+1/16+...+1/81+1/100 . Chung minh rang : A > 65/132
d.Cho B = 12/(2 . 4 ) ^ 2 + 20/ (4 . 6) ^2 + ...........+ 388/ ( 96 . 98 ) ^ 2 + 396/ ( 98 . 100 ) ^2 .Hay so sanh B voi 1 /4
A= 1+2+2^2+...+2^2018
B= 3+3^2+3^3+...+3^2017
C= 1+5^2+5^4+...+5^2018
D= 1.3+2.4+3.5+...+99.101
1. \(B=\frac{12}{\left(2.4\right)^2}+\frac{20}{\left(4.6\right)^2}+...+\frac{388}{\left(96.98\right)^2}+\frac{396}{\left(98.100\right)^2}\)
So sánh \(B\) với \(\frac{1}{4}\)
2. SO sánh \(A=\frac{2015}{2016}+\frac{2016}{2017}+\frac{2017}{2018}\) và \(B=\frac{2015+2016+2017}{2016+2017+2018}\)
tính 2.4+3.5+4.6+5.7+6.8+7.9+8.10+...+97.99+98.100
Thực hiện phép tinh sau:
\(\frac{1}{1.3}+\frac{1}{2.4}+\frac{1}{3.5}+\frac{1}{4.6}+\frac{1}{5.7}+\frac{1}{6.8}+\frac{1}{7.9}+\frac{1}{8.10}\)
Tính tổng S=1/1.3 +1/2.4+ 1/3.5+....+1/7.9 +1/8.10