Bài 1: (2,0 điểm) Tính hợp lí (nếu có thể) a) $\frac{-15}{14}$ : $\frac{17}{23}$ - $\frac{15}{14}$ : $\frac{17}{11}$ - $\frac{6}{7}$ b) ($\frac{-5}{3}$ + $\frac{-3}{2}$) : $\frac{17}{13}$ + ($\frac{7}{2}$ + $\frac{-1}{3}$) : $\frac{17}{13}$ c) 3².$\frac{1}{243}$.81².$\frac{1}{3³}$ d) (4.$2^{5}$) : ($2^{3}$.$\frac{1}{16}$)

Bài `1:`

`a)(-15)/14:17/23-15/14:17/11-6/7`

`=(-15)/14. 23/17+(-15/14). 11/17-6/7`

`=-15/14. (23/17+11/17)-6/7`

`=-15/14. 2-6/7`

`=-15/7-6/7`

`=-3`

`b)((-5)/3+(-3)/2):17/13+(7/2+(-1)/3):17/13`

`=-19/6. 13/17+19/6. 13/17`

`= 13/17 . (-19/6+19/6)`

`=13/17.0`

`=0`

`c)3^2. 1/243. 81^2. 1/3^3`

`=3^2. (1/3)^5. (3^4)^2. 1/3^3`

`=3^2. 1/3^5. 3^8. 1/3^3`

`=(3^2. 3^8). (1/3^5. 1/3^3)`

`=(3^(2+8)) . (1/3^(5+3))`

`=3^10. 1/3^8`

`=3^10 : 3^8`

`=3^(10-8)`

`=3^2`

`=9`

`d)(4.2^5):(2^3. 1/16)`

`=(2^2. 2^5):(2^3. 1/2^4)`

`=(2^(2+5)) : (2^3 . 1/2^4)`

`=2^7:1/2`

`=2^7. 2`

`=2^(7+1)`

`=2^8`

`=256`