(1/3+1/3^2+1/3^3+1/3^4).3^5+(1/3^5+1/3^6+1/3^7+1/3^8).3^9+.....+(1/3^97+1/3^98+1/3^99+1/3^100).3^101
Tính giá trị của biểu thức:
A=(1/3+1,3^2+1/3^3+1/3^4).3^5+(1/3^5+1/3^6+1/3^7+1/3^8).3^9+...+(1/3^97+1/3^98+1/3^99+1/3^100).3^101
Tính:
\(3^5.\left(\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}\right)+\left(\frac{1}{3^5}+\frac{1}{3^6}+\frac{1}{3^7}+\frac{1}{3^8}\right).3^9+....+\left(\frac{1}{3^{97}}+\frac{1}{3^{98}}+\frac{1}{3^{99}}+\frac{1}{3^{100}}\right).3^{101}\)
a) [ 6.(-1/3)^3 - 3. (-1/3)+ 1] - (-1/3 - 1)
b) ( 6^3+ 3. 6^2+ 3^3 ) : 13
c) 9/10-1/90-1/72-1/56-1/42-1/30-1/20-1/12-1/6-1/2
,E= - 1/3 + 1/(3 ^ 2) - 1/(3 ^ 3) + 1/(3 ^ 4) -...+ 1 3^ 50 - 1 3^ 51
\(\left(\dfrac{1}{3}+\dfrac{1}{3^2}+\dfrac{1}{3^3}+\dfrac{1}{3^4}\right).3^5+\left(\dfrac{1}{3^5}+\dfrac{1}{3^6}+\dfrac{1}{3^7}+\dfrac{1}{3^8}\right).3^9\)
-1/3+1/3^2-1/3^3+1/3^4-...+1/3^50-1/3^51
cần gấp
B= 1/3+1/3^2+1/3^3+1/3^4+.......+1/3^2019+1/3^2020
Cho B = 1/3 + 1/3^2 + 1/3^3 + 1/3^4 + ... + 1/3^2004 + 1/3^2005
Chứng minh rằng B < 1/2
Giúp mình giải câu này với Tính B= -1/3+1/3^2-1/3^3+1/3^4-1/3^5+...+1/3^50-1/3^51