Question

tính nhanh hộ mình câu này với ; 5+5/3+5/9+5/27+5/81

 

có cách làm nha

 

Answer 1

  5 + 5/3 + 5/9 + 5/27 + 5/81

= 5/1 + 5/3 + 5/9 + 5/27 + 5/81

= 405/81 + 135/81 + 15/81 + 5/81

= 605/81

Answer 2

\(\frac{605}{81}\)nha bạn

Answer 3

A=5+5/3+5/9+5/27+5/81
=5.(1+1/3+1/9+1/27+1/81)
=5(1+1/1.3+1/3^2+1/3^3+1/3^4)
Đat M=1+1/1.3+1/3^2+1/3^3+1/3^4
-->3M=3+1+1/3+1/3^2+1/3^3
-->3M-M=(3+1+1/3+1/3^2+1/3^3) - (1+1/1.3+1/3^2+1/3^3+1/3^4)
-->2M=3-1/3^4
-->M=121/81
--->A=5.121/81=605/81

Answer 4

 1/5+5/9+4/5+1/9+3/9 bằng bao nhiêu