\(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\)

\(\Leftrightarrow\frac{\frac{17}{4}}{\frac{23}{8}}=\frac{x}{1,61}\)

\(\Leftrightarrow\frac{34}{23}=\frac{x}{1,61}\)

\(\Leftrightarrow x=\frac{34}{23}.1,61\)

\(\Leftrightarrow x=\frac{119}{50}\)

a) - 0,52 : x = - 9,36 : 16,38

- 0,52 : x = \(-\frac{4}{7}\)

\(x=\left(-0,52\right):\left(-\frac{4}{7}\right)=\frac{91}{100}=0,91\)

b) \(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\)

\(\frac{\frac{17}{4}}{\frac{23}{8}}=\frac{x}{1,61}\)

\(\frac{x}{1,61}=\frac{34}{23}\)

\(x=\frac{34}{23}.1,61=2,38\)

a) \(\frac{x}{27}=\frac{-2}{3,6}\Leftrightarrow x=\frac{-2.27}{3,6}=-15\)

b) \(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\Leftrightarrow\frac{4,25}{2,875}=\frac{x}{1,61}\Leftrightarrow x=\frac{4,25.1,61}{2,875}=2,38\)

a) \(\frac{x}{27}=-\frac{2}{3,6}\Rightarrow x=\frac{-2.27}{3,6}=-15\)

b) \(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\Rightarrow\frac{\frac{17}{4}}{\frac{23}{8}}=\frac{x}{1,61}\Leftrightarrow\frac{17}{4}\cdot\frac{8}{23}=\frac{x}{1,61}\)

 \(\frac{34}{23}=\frac{x}{1,61}\Rightarrow x=\frac{1,61.34}{23}=2,38\)

a, ta có:27:3,6=7,5

=>-2x7,5=15

vậy x cần tìm là 15

b, -0,52:x=\(-\frac{4}{7}\)

\(\frac{-13}{25}\): x=\(\frac{-4}{7}\)

x=\(\frac{-13}{25}:\frac{-4}{7}\)

x=0,91

a)\(\frac{x}{27}=\frac{-2}{3,6}\)

=>x.3,6=27.(-2)

=>x.3,6=-54

=>x=-15

b)-0,52:x=-9,36:16,38

=>-0,52:x=-4/7

=>x=0,91

c)\(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\)

=>\(2\frac{7}{8}.x=4\frac{1}{4}.1,61\)

=>\(2\frac{7}{8}.x=\frac{2737}{400}\)

=>x=\(\frac{119}{50}\)

a,\(\frac{x}{27}=-\frac{2}{3,6}\)

\(\Leftrightarrow x.3,6=27.-2\)

\(\Leftrightarrow x.3,6=-54\)

\(\Leftrightarrow x=-15\)

b,\(-0,52\div x=-9,36\div16,38\)

\(\Leftrightarrow-0,52\div x=-\frac{4}{7}\)

\(\Leftrightarrow x=\frac{91}{100}\)

c,\(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\)

\(\Leftrightarrow\frac{4,25}{2,875}=\frac{x}{1,61}\)

\(\Leftrightarrow x.2,875=4,25.1,61\)

\(\Leftrightarrow x.2,875=6,8425\)

\(\Leftrightarrow x=2,38\)

\(\frac{x}{27}=-\frac{2}{3,6}\)

\(x=\frac{-2\times27}{3,6}\)

\(x=-15\)

***

\(\frac{-0,52}{x}=\frac{-9,36}{16,38}\)

\(x=\frac{-0,52\times16,38}{-9,36}\)

\(x=0,91\)

***

\(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\)

\(\frac{4,25}{2,875}=\frac{x}{1,61}\)

\(x=\frac{4,25\times1,61}{2,875}\)

\(x=2,38\)

\(a.\)

\(\frac{x}{27}=\frac{-2}{3,6}\)

\(\Rightarrow x=\frac{\left(-2\right).27}{3,6}\)

\(\Rightarrow x=\frac{-54}{3,6}\)

\(\Rightarrow x=-15\)

Vậy :        \(x=-15\)

\(b.\)

\(-0,52:x=-9,36:16,38\)

\(\Rightarrow\frac{-0,52}{x}=-\frac{4}{7}\)

\(\Rightarrow x=\frac{-0,52.7}{-4}\)

\(\Rightarrow x=0,91\)

Vậy :         \(x=0,91\)

\(c.\)

\(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\)

\(\Rightarrow\frac{\frac{17}{4}}{\frac{23}{8}}=\frac{x}{1,61}\)

\(\Rightarrow\frac{17}{4}.\frac{8}{23}=\frac{x}{1,61}\)

\(\Rightarrow\frac{34}{23}=\frac{x}{1,61}\)

\(\Rightarrow x=\frac{1,61.34}{23}\)

\(\Rightarrow x=\frac{119}{50}\)

Vậy :         \(x=\frac{119}{50}\)

Bài 1:

a) \(\frac{x}{-15}=\frac{-60}{x}\Rightarrow x^2=\left(-60\right).\left(-15\right)=900\Rightarrow x=\orbr{\begin{cases}30\\-30\end{cases}}\)

Bài 2: Đặt \(\frac{x}{4}=\frac{y}{7}=k\Rightarrow x=4k;y=7k\)

\(\Rightarrow xy=4k.7k=28k^2=112\)

\(\Rightarrow k^2=4\Rightarrow k=\pm2\)

\(\Rightarrow\orbr{\begin{cases}x=4.2=8\\x=-4.2=-8\end{cases}}\)

Và \(\orbr{\begin{cases}y=7.2=14\\y=-7.2=-14\end{cases}}\)

Bài 3: \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1x\right)\)

\(\Rightarrow\frac{4}{3}:\frac{4}{5}=\frac{2}{3}:\frac{1}{10}x\Rightarrow\frac{5}{3}=\frac{2}{3}:\frac{1}{10}x\)

\(\Rightarrow\frac{1}{10}x=\frac{2}{5}\Rightarrow x=4\)

Mk trả lời nốt bài 4 hộ bn MMS_Hồ Khánh Châu nha:
Bài 4:
Gọi x là giá trị chung của 2 phân số trên.
Ta có: \(\frac{a}{b}=\frac{c}{d}=x\)
\(\Rightarrow a=x.b \)
      \(c=x.d\)
Ta lại có: 
\(\frac{a+c}{b+d}=\frac{x.b+x.d}{b+d}=\frac{x.\left(b+d\right)}{b+d}=x\)
Và \(\frac{a}{b}=x\)
\(\Rightarrow\frac{a}{b}=\frac{a+c}{b+d}\)
Vậy \(\frac{a}{b}=\frac{a+c}{b+d}\)
Hk tốt nha