Câu 9 (2,5 điểm). Thưc̣ hiêṇ phép tính (tính hơp̣ lí nếu có): a) $\frac{5}{12}$ - $\frac{1}{5}$ b) 6.(-$\frac{1}{3}$)² - $\frac{1}{9}$ c) $(\frac{1}{5})^{5}$ : $(\frac{1}{5})^{3}$ - $(\frac{-1}{3})^{3}$ : $(\frac{-1}{3})^{2}$ d) (1 - $\frac{2}{3}$ + $\frac{1}{2}$) - (2 + $\frac{1}{3}$ - 1,5)

Đáp án:

`1) 5/12 -1/5 = 25/60 -12/60 = 13/60`

`2) 6.(-1/3)^2 -1/9`

`= 6.(1/9) -1/9`

`= 1/9.(6-1) `

`= 1/9.(5)`

`= 5/9`

`3) (1/5)^5 : (1/5)^3 - (-1/3)^3 : (-1/3)^2`

`= (1/5)^2 - (-1/3)`

`= 1/25 +1/3`

`= (3+25)/75 `

`= 28/75`

`4) (1-2/3+1/2)-(2+1/3-1,5)`

`= 1-2/3+1/2-2-1/3+3/2`

`= (1-2)+(-2/3-1/3)+(1/2+3/2)`

`= -1 -1 +2 `

`= 0`