\(a,x=\dfrac{18.7}{14}\)

\(x=\dfrac{8}{2}=4\)

\(b,\)\(x=6.5:1\dfrac{3}{4}\)

\(x=30:\dfrac{7}{4}\)

\(x=30.\dfrac{4}{7}=\dfrac{120}{7}\)

\(c,-x=\)\(\dfrac{5,7.0,45}{0,35}\)

\(-x=\)\(\dfrac{2,565}{0,35}\)

\(x=\dfrac{-2,565}{0,35}\)

a)\(\dfrac{x}{7}=\dfrac{18}{14}\) b) 6:x=\(1\dfrac{3}{4}\):5 c) 5,7 : 0,35= -x: 0,45

\(\Rightarrow\) x.14= 18.7 \(\Rightarrow\) 6:x=\(\dfrac{7}{20}\) \(\Rightarrow\)\(\dfrac{114}{7}=\dfrac{-x}{0,45}\)

\(\Rightarrow\)x.14=126 \(\Rightarrow\)x=\(\dfrac{10}{21}\) \(\Rightarrow53,1=\left(-x\right).7\)

\(\Rightarrow\)x=9 \(\Rightarrow x=7,3\)

CHÚC BẠN HỌC TỐT

a, \(\dfrac{x}{7}\)=\(\dfrac{18}{14}\)

\(x.14=7.18\)

\(x.14=126\)

\(\Rightarrow x=9\)

b,\(6:x=1^3_4:5\)

\(6:x=\dfrac{7}{20}\)

\(x=\dfrac{7}{120}\)

a/ \(\dfrac{x}{7}=\dfrac{18}{14}\)

\(\Leftrightarrow14x=7.18\)

\(\Leftrightarrow14x=126\)

\(\Leftrightarrow x=9\)

Vậy ....

b/ \(6:x=1\dfrac{3}{4}:5\)

\(\Leftrightarrow6:x=\dfrac{7}{20}\)

\(\Leftrightarrow x=\dfrac{120}{7}\)

Vậy ...........

bao giờ bạn cần vậy

nói đi mik giải giùm cho nha!

\(\dfrac{x}{7}=\dfrac{18}{14}\)

\(\Rightarrow x=\dfrac{18.7}{14}=9\)

Vậy x=4

a) \(\frac{x}{7}=\frac{18}{14}\)

\(\frac{x}{7}=\frac{9}{7}\)

\(\Rightarrow x=9\)

b) \(6:x=1\frac{3}{4}:5\)

\(6:x=\frac{7}{4}.\frac{1}{5}\)

\(6:x=\frac{7}{20}\)

\(x=6:\frac{7}{20}\)

\(x=\frac{120}{7}\)

vay \(x=\frac{120}{7}\)

c) \(\frac{5,7}{0,35}=\frac{-x}{0,45}\)

\(\Rightarrow-0,35x=5,7.0,45\)

\(\Rightarrow-0,35x=2,565\)

\(\Rightarrow x=\frac{-2,565}{0,35}\)

\(\Rightarrow x=\frac{-513}{70}\)

vay \(x=\frac{-513}{70}\)

a)\(\dfrac{x}{3}=\dfrac{y}{7}=\dfrac{x+y}{3+7}=\dfrac{20}{10}=2\)

\(\dfrac{x}{3}=2\Rightarrow x=6\)

\(\dfrac{y}{7}=2\Rightarrow y=14\)

b)\(\dfrac{x}{5}=\dfrac{y}{2}=\dfrac{x-y}{5-2}=\dfrac{6}{3}=2\)

\(\dfrac{x}{5}=2\Rightarrow x=10\)

\(\dfrac{y}{2}=2\Rightarrow y=4\)

Câu 2: 

Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:

\(\dfrac{x}{2}=\dfrac{y}{4}=\dfrac{z}{6}=\dfrac{x-y+z}{2-4+6}=\dfrac{8}{8}=1\)

Do đó: x=2; y=4; z=6

a)x=18*7/14=9

b)x=6.5/(7/4)=120/7

c)-x=5,7*0,45/0,35=513/70

\(\begin{array}{l}a)\dfrac{x}{6} = \dfrac{{ - 3}}{4}\\x = \dfrac{{( - 3).6}}{4}\\x = \dfrac{{ - 9}}{2}\end{array}\)

Vậy \(x = \dfrac{{ - 9}}{2}\)

\(\begin{array}{l}b)\dfrac{5}{x} = \dfrac{{15}}{{ - 20}}\\x = \dfrac{{5.( - 20)}}{{15}}\\x = \dfrac{{ - 20}}{3}\end{array}\)

Vậy \(x = \dfrac{{ - 20}}{3}\)

a) \(\frac{x}{7}=\frac{18}{14}\)

\(\Rightarrow\frac{x}{7}=\frac{9}{7}\)

\(\Rightarrow x=7\)

Vậy x=7

b)\(6:x=1\frac{3}{4}:5\)

\(\frac{6}{x}=\frac{7}{4}:5\)

\(\frac{6}{x}=\frac{7}{20}\)

\(\Rightarrow6.20=7x\)

\(\Rightarrow120=7.x\)

\(\Rightarrow x=\frac{120}{7}\)

Vậy \(x=\frac{120}{7}\)

a) Ta có :

\(x\)/7 = 18/14

=> \(x\) = (7 x 18)/14

x= 9

b) Ta có:

6 : \(x\)= 1(3/4) : 5

=> \(x\)= (6 x 5)/1(3/4)

= \(\frac{30}{\frac{7}{4}}\)

c) Ta có:

5,7 : 0,35 = -\(x\):0,45

=> -\(x\)= (5,7 x 0,45)/ 0,35

\(x\)=5130/7

Bài 4 câu c) và x-y+y hay x-y+z vậy bạn

1 a) \(\dfrac{\left(-2\right)}{5}\)= \(\dfrac{-6}{15}\); \(\dfrac{15}{-6}\)= \(\dfrac{5}{-2}\); \(\dfrac{-6}{-2}\)= \(\dfrac{15}{5}\); \(\dfrac{-2}{-6}\)= \(\dfrac{5}{15}\)

1.b)bn làm tương tự như bài 1 a)