\(a,\dfrac{x}{4}=\dfrac{16}{128}\\ \Leftrightarrow128x=4.16\\ \Leftrightarrow128x=64\\ \Leftrightarrow x=\dfrac{1}{2}\)

Vậy...

\(b,1\dfrac{5}{6}=\dfrac{-x}{5}\\ \Leftrightarrow-6x=25\\ \Leftrightarrow x=-\dfrac{25}{6}\)

Vậy...

\(c,4,25:8=-3,5:x\\ \Leftrightarrow4,25x=-3,5.8\\ \Leftrightarrow x=-28:4,25\\ \Leftrightarrow x=-\dfrac{112}{17}\)

Vậy...

Câu a :

\(\dfrac{x}{4}=\dfrac{16}{128}\) \(\Leftrightarrow x.128=4.16\) \(\Rightarrow x=\dfrac{1}{2}\)

Câu b :

\(1\dfrac{5}{6}=-\dfrac{x}{5}\) \(\Leftrightarrow11.5=-x.6\) \(\) \(\Rightarrow-x=-\dfrac{55}{6}\)

Câu c :

\(\dfrac{4,25}{8}=\dfrac{-3,5}{x}\) \(\Leftrightarrow4,25.x=8.-3,5\) \(\Rightarrow x=-\dfrac{112}{17}\)

a,Ta có : x.128=16.4

x.128=64

Suy ra : x=1/2

b,\(1\dfrac{5}{6}=\dfrac{11}{6}\)

Ta có ; 11.5=-x.6

-x.6=55

Suy ra : x=-55/6

c,Ta có : 4,25.x=-3,5.8

4,25.x=-28

Suy ra : x=-112/17

a) \(\dfrac{x}{2}=\dfrac{y}{3}\Rightarrow\dfrac{x^2}{4}=\dfrac{y^2}{9}=\dfrac{x^2-y^2}{4-9}=\dfrac{-16}{-5}=\dfrac{16}{5}\)

\(\Rightarrow\left\{{}\begin{matrix}x^2=4.\dfrac{16}{5}\\y^2=9.\dfrac{16}{5}\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x=\pm\left(2.\dfrac{4}{\sqrt[]{5}}\right)=\pm\dfrac{8\sqrt[]{5}}{5}\\y=\pm\left(3.\dfrac{4}{\sqrt[]{5}}\right)=\pm\dfrac{12\sqrt[]{5}}{5}\end{matrix}\right.\)

\(\dfrac{y}{4}=\dfrac{z}{5}\Rightarrow z=\dfrac{5}{4}y=\dfrac{5}{4}.\left(\pm\dfrac{12\sqrt[]{5}}{5}\right)=\pm3\sqrt[]{5}\)

b) \(\left|2x+3\right|=x+2\)

\(\Rightarrow\left[{}\begin{matrix}2x+3=x+2\\2x+3=-x-2\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-1\\3x=-5\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-1\\3x=-\dfrac{5}{3}\end{matrix}\right.\)

Đính chính

Dòng cuối \(3x=-\dfrac{5}{3}\rightarrow x=-\dfrac{5}{3}\)

a) \(x-\dfrac{5}{6}=\dfrac{1}{2}\)

           \(x=\dfrac{1}{2}+\dfrac{5}{6}\)

           \(x=\dfrac{4}{3}\)

vậy x = ....

b) \(3\dfrac{1}{3}x+16\dfrac{3}{4}=-13,25\)

    \(\dfrac{10}{3}\)\(x+\dfrac{67}{4}=-13,25\)

     \(\dfrac{10}{3}x=\left(-13,25\right)-\dfrac{67}{4}\)

      \(\dfrac{10}{3}x=-30\)

          \(x=\left(-30\right):\dfrac{10}{3}\)

         \(x=-9\)

vậy x =...

sai mog bn thông cảm!!!

\(a.\)

\(\dfrac{x}{4}=\dfrac{16}{128}\)

\(\Rightarrow x=\dfrac{16.4}{128}=\dfrac{1}{2}\)

\(b.\)

\(1\dfrac{5}{6}=-\dfrac{x}{5}\)

\(\Rightarrow\dfrac{11}{6}=-\dfrac{x}{5}\)

\(\Rightarrow x=\dfrac{11.\left(-5\right)}{6}=-\dfrac{55}{6}\)

\(c.\)

\(4,25:8=-3,5:x\)

\(\Rightarrow\dfrac{4,25}{8}=\dfrac{-3,5}{x}\)

\(\Rightarrow x=\dfrac{-3,5.8}{4,25}=-\dfrac{112}{17}\)

\(a)\dfrac{x}{4}=\dfrac{16}{128}\)

\(\Rightarrow\dfrac{16}{128}.4=\dfrac{1}{2}\)

\(b)1\dfrac{5}{6}=\dfrac{-x}{5}\)

\(\Rightarrow x=\dfrac{11}{6}.\left(-5\right)=\dfrac{-55}{6}\)

\(c)4,25:8=-3,5:x\)

\(\Rightarrow\dfrac{4,25}{8}=\dfrac{-3,5}{x}\)

\(\Rightarrow x=\dfrac{-3,5.8}{4,25}=\dfrac{-112}{17}\)

Chúc bạn học tốt!

a)4/5+x=2/3

x=2/3-4/5

x=-2/15

b)-5/6-x=2/3

x=-5/6-2/3

x=-3/2

c)1/2x+3/4=-3/10

1/2x=-3/10-3/4

1/2x=-21/20

x=-21/20:1/2

x=-21/10

d)x/3-1/2=1/5

x/3=1/5+1/2

x/3=7/10

10x/30=21/30

10x=21

x=21:10

x=21/10

a: =>x-3/4=1/6-1/2=1/6-3/6=-2/6=-1/3

=>x=-1/3+3/4=-4/12+9/12=5/12

b: =>x(1/2-5/6)=7/2

=>-1/3x=7/2

hay x=-21/2

c: (4-x)(3x+5)=0

=>4-x=0 hoặc 3x+5=0

=>x=4 hoặc x=-5/3

d: x/16=50/32

=>x/16=25/16

hay x=25

e: =>2x-3=-1/4-3/2=-1/4-6/4=-7/4

=>2x=-7/4+3=5/4

hay x=5/8

a. x²=16.4

    x²=64

vì x<0 => x= -8

b: Tỉ số giữa 48 giờ và 3,2 giờ là:

48:3,2=15:1

c: \(\dfrac{-36}{7}\cdot\dfrac{2}{3}=\dfrac{-72}{21}=\dfrac{-24}{7}\)