Đáp án:

$1) 2x-3=x+1/2$

$⇔ 2x-x=1/2+3$

$⇔ x = 3,5$

$2)\dfrac{-8}{19}.$ $\dfrac{25}{34}.$ $\dfrac{-17}{5}.$ $\dfrac{19}{-27}$

$=(\dfrac{-8}{19}.$ $\dfrac{19}{-27}).$ $\dfrac{25}{34}.$ $\dfrac{-17}{5}$

$=\dfrac{8}{27}.$ $\dfrac{-425}{170}$

$=\dfrac{8}{27}.$ $\dfrac{-5}{2}$

$=\dfrac{-40}{54}$

$=\dfrac{-20}{27}$

$3)15\dfrac{1}{4}:$ $\dfrac{-5}{7}-$ $25\dfrac{1}{4}:$ $\dfrac{-5}{7}$

$=(15\dfrac{1}{4}-$ $25\dfrac{1}{4}):$ $\dfrac{-5}{7}$

$=-10.\dfrac{7}{-5}$

$=\dfrac{-70}{-5}$

$=14$

BẠN THAM KHẢO NHA!!!

1) $2x-3=x+\dfrac{1}{2}$

$2x-3-x-\dfrac{1}{2}=0$

$(2x-x)+(-3-\dfrac{1}{2})=0$

$x-\dfrac{7}{2}=0$

$⇒x=\dfrac{7}{2}$

2) $\dfrac{-8}{19}.\dfrac{25}{34}.\dfrac{-17}{5}.\dfrac{19}{-27}$

`=((-8)/19. 19/(-27)).(25/34. (-17)/5)`

`=((-8)/27).(5/2. (-2)/1)`

$=\dfrac{-8}{27}.(-5)$

$=\dfrac{40}{27}$

3) $15\dfrac{1}{4}:\dfrac{-5}{7}-25\dfrac{1}{4}:\dfrac{-5}{7}$

$=15\dfrac{1}{4}.\dfrac{-7}{5}-25\dfrac{1}{4}.\dfrac{-7}{5}$

$=\dfrac{-7}{5}.(15\dfrac{1}{4}-25\dfrac{1}{4})$

$=\dfrac{-7}{5}.(-10)$

$=-7.(-2)=14$