Bài 1: (2,0 điểm) a) Thực hiện phép tính: $\frac{1}{3}$ + |$\frac{- 1}{6}$| - $\sqrt{\frac{9}{4}}$ - ($\frac{-2}{5}$)² b) Tính hợp lý nếu có thể: (1$\frac{5}{9}$ + $\frac{-7}{11}$) : $\frac{1}{2}$ + ($\frac{4}{9}$ - $\frac{4}{11}$) : $\frac{1}{2}$ c) Tìm x biết, $\frac{2}{3}$x + 0,25 = 2$\frac{1}{4}$

Bài `1` :

`a) 1/3+|(-1)/6|-\sqrt{9/4} -((-2)/5)^2`

`=1/3+1/6-\sqrt{(3/2)^2}-4/25`

`=1/3+1/6-3/2-4/25`

`=2/6+1/6-9/6-4/25`

`= -1-4/25`

`=-25/25-4/25=-29/25`

Vậy `1/3+|(-1)/6|-\sqrt{9/4} -((-2)/5)^2 =-29/25`

`b)(1 5/9+ (-7)/11):1/2+(4/9-4/11):1/2`

`=(14/9+(-7)/11):1/2+(4/9-4/11):1/2`

`=(14/9+(-7)/11+4/9-4/11):1/2`

`=[(14/9+4/9)-(7/11+4/11)]:1/2`

`=(2-1):1/2=1:1/2=2`

Vậy `(1 5/9+ (-7)/11):1/2+(4/9-4/11):1/2 =2`

`c)2/3x+0,25=2 1/4`

`=>2/3x+1/4=2 1/4`

`=>2/3x=2 1/4-1/4`

`=>2/3x=2`

`=>x=2:2/3`

`=>x=3`

Vậy `x=3`