\(\text{Đ}\text{ặt}\text{ }A=1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}\)

\(\Rightarrow3A=3+1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}\)

\(\Rightarrow3A-A=3-\frac{1}{81}\)

\(\Rightarrow2A=\frac{242}{81}\)

\(\Rightarrow A=\frac{242}{81}:2=\frac{121}{81}\)

4/9 > 3/10

k cho mk nha

4/9=0,4444444444444444444444.

3/10=0,3

4/9>3/10.   

4/9  >  3/10

Chúc bạn học tốt !

Ta có :

\(\frac{12}{13}=1-\frac{1}{13}\)

\(\frac{13}{14}=1-\frac{1}{14}\)

Vì \(\frac{1}{13}>\frac{1}{14}\)nên \(1-\frac{1}{13}< 1-\frac{1}{14}\)

Vậy \(\frac{12}{13}< \frac{13}{14}\)

Ta thấy:

\(\frac{12}{13}=1-\frac{1}{13}\)

\(\frac{13}{14}=1-\frac{1}{14}\)

Vì 13<14.

=>\(\frac{1}{13}>\frac{1}{14}\)

=>\(1-\frac{1}{13}< 1-\frac{1}{14}\)

=>\(\frac{12}{13}< \frac{13}{14}\)

Vậy......

\(\frac{12}{13}\)và \(\frac{13}{14}\)

Ta có : \(\frac{12}{13}=\frac{12}{13}+\frac{1}{13}\)  ;   \(\frac{13}{14}=\frac{13}{14}+\frac{1}{14}\)

Ta thấy \(\frac{1}{13}>\frac{1}{14}\)=> \(\frac{12}{13}< \frac{13}{14}\)

1-8/9=1/9   1-9/10=1/10   1/9 >1/10 nen 8/9<9/10   

Vì    \(\frac{12}{49}< \frac{13}{49}\)

        \(\frac{13}{49}< \frac{13}{47}\)

Nên \(\frac{12}{49}< \frac{13}{47}\)

Ta có 13/47>13/49

Mà 13/49>12/49

=> 12/49<13/47

\(\frac{12}{49}\)và \(\frac{13}{47}\Rightarrow12.47\)và \(49.13\)\(\Rightarrow564\)và \(637\)

vì 564<637

nên \(\frac{12}{49}< \frac{13}{47}\)

a)MSC nhỏ nhất:18 

b)24

mẫu số nhỏ nhất là 18

24

a) MSC: 18

b)MSC: 24

75/77< 457/459< 2003/2005

5/6 <6/7

5/6 = 35/42

6/7 = 36/42

35/42 < 36/42

Vậy 5/6 < 6/7

5/6<6/7