Bài1: tính

Chỉ bài 1 thôi ạ

`3/5+5/9=27/45+25/45=52/45`

`2 2/7×5 3/5=16/7×28/5=448/35=64/5`

`1/2÷3/7=1/2×7/3=7/6`

`3 2/11÷2 4/11=35/11÷26/11=36/11×11/26=35/26`

Đáp án+Giải thích các bước giải:

$\text{a) $\dfrac{3}{5}$ + $\dfrac{5}{9}$}$

$\text{= $\dfrac{27}{45}$ + $\dfrac{25}{49}$}$

$\text{= $\dfrac{52}{45}$}$

$\text{b) 2$\dfrac{2}{7}$ $\times$ 5$\dfrac{3}{5}$}$

$\text{= $\dfrac{16}{7}$ $\times$ $\dfrac{28}{5}$}$

$\text{= $\dfrac{448}{35}$ = $\dfrac{64}{5}$}$

$\text{c) $\dfrac{1}{2}$ : $\dfrac{3}{7}$}$

$\text{= $\dfrac{1}{2}$ × $\dfrac{7}{3}$}$

$\text{= $\dfrac{7}{6}$}$

$\text{d) 3$\dfrac{2}{11}$ : 2$\dfrac{4}{11}$}$

$\text{= $\dfrac{35}{11}$ : $\dfrac{26}{11}$}$

$\text{= $\dfrac{35}{11}$ × $\dfrac{11}{26}$}$

$\text{= $\dfrac{35}{26}$}$