Câu 9 (2,0 điểm). Thực hiện phép tính (tính hợp lý nếu có thể): 1. $\frac{3}{4}$ + 1$\frac{2}{3}$ - $\frac{7}{9}$ 2. $\frac{1}{7}$.$(\frac{4}{3})^{2}$ - $\frac{1}{7}$ : $\frac{9}{11}$ 3. (-$\frac{4}{9}$ + $\frac{3}{5}$) : 1$\frac{1}{5}$ + ($\frac{1}{5}$ - $\frac{5}{9}$) : 1$\frac{1}{5}$ 4. 0,5.$\frac{4}{9}$ + ($\frac{1}{3}$ - 1,5)² - $(\frac{2}{3})^{9}$ : $(\frac{2}{3})^{7}$

1, `3/4 + 1 2/3 - 7/9`

`= 3/4 + 5/3 - 7/9`

`= 27/36 + 60/36 - 28/36`

`= 59/36`

2, `1/7 . (4/3)^2 - 1/7 : 9/11`

`= 1/7 . 16/9 - 1/7 . 11/9`

`= 1/7 . (16/9 - 11/9)`

`= 1/7 . 5/9`

`= 5/63`

3, `(-4/9 + 3/5) : 1 1/5 + (1/5 - 5/9) : 1 1/5`

`= 7/45 : 6/5 + (-16)/45 : 6/5`

`= [7/45 + (-16)/45] : 6/5`

`= (-1)/5 . 5/6`

`= -1/6`

4, `0,5 . 4/9 + (1/3 - 1,5)^2 - (2/3)^9 : (2/3)^7`

`= 1/2 . 4/9 + (1/3 - 3/2)^2 - (2/3)^2`

`= 2/9 + (-7/6)^2 - 4/9`

`= 2/9 + 49/36 - 4/9`

`= 8/36 + 49/36 - 16/36`

`= 41/36`