biết làm ở đề bài khác mà bài này khó quá

Trả lời :

\(\frac{y}{4}=\frac{36}{y}\)

\(=>y=12\)

\(\frac{y}{4}=\frac{36}{y}\)

\(\Rightarrow y.y=4.36\)

\(\Rightarrow y^2=144\)

\(\Rightarrow y^2=\left(\pm12\right)^2\)

Vậy \(y=\pm12\)

\(\frac{3}{-x}=\frac{x^2}{9}\)

\(\Rightarrow-x.x^2=3.9\)

\(-x^3=27\)

\(-x^3=3^3\)

\(\Rightarrow-x=3\)

\(\Rightarrow x=-3\)

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

\(\Rightarrow x.y=6.7\)

\(x.y=56\)

\(\Rightarrow x.y\inƯ\left(56\right)\)

\(\Rightarrow\orbr{\begin{cases}x=56\\y=1\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=1\\y=56\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-56\\x=-1\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-1\\y=-56\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=2\\y=28\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=28\\y=2\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-2\\y=-28\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-28\\y=-2\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=4\\y=14\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=14\\y=4\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-4\\y=-14\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-14\\y=-4\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=7\\y=8\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=8\\y=7\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-7\\y=-8\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-8\\y=-7\end{cases}}\)

Vậy ..

chúc bạn học tốt

<=>\(\frac{24-18-X}{6}\)=\(\frac{3X}{6}\)

<=>\(6-X=3X\)

<=>\(-4X=-6\)

<=>\(X=\frac{3}{2}\)

a) \(\frac{3}{2}-\frac{5}{6}:x=\frac{5}{15}-\frac{3}{15}\)

\(\Leftrightarrow\frac{3}{2}-\frac{5}{6}:x=\frac{2}{15}\)

\(\Leftrightarrow\frac{5}{6}:x=\frac{3}{2}-\frac{2}{15}\)

\(\Leftrightarrow\frac{5}{6}:x=\frac{41}{30}\)

\(\Leftrightarrow x=\frac{5}{6}:\frac{41}{30}\)

\(\Leftrightarrow x=\frac{25}{41}\)

b) \(x-\frac{6}{7}.\frac{14}{8}=\frac{1}{2}-\frac{2}{5}\)

\(\Leftrightarrow x-\frac{3}{2}=\frac{1}{10}\)

\(\Leftrightarrow x=\frac{1}{10}+\frac{3}{2}\)

\(\Leftrightarrow x=\frac{8}{5}\)

c) \(x:\frac{6}{5}+\frac{2}{3}=\frac{7}{3}\)

\(\Leftrightarrow x:\frac{6}{5}=\frac{7}{3}-\frac{2}{3}\)

\(\Leftrightarrow x:\frac{6}{5}=\frac{5}{3}\)

\(\Leftrightarrow x=\frac{5}{3}.\frac{6}{5}\)

\(\Leftrightarrow x=2\)

huyền ngốc

\(\trac{3}{2}

12 phần 25 trừ cho 14 phần 5 bằng bao nhiêu

8==D LOL

     Bài 1:

\(x\) \(\times\) \(\dfrac{15}{16}\) - \(x\) \(\times\) \(\dfrac{4}{16}\) = 2

\(x\) \(\times\) (\(\dfrac{15}{16}\) - \(\dfrac{4}{16}\)) = 2

\(x\) \(\times\) \(\dfrac{11}{16}\) = 2

\(x\) = 2 : \(\dfrac{11}{16}\)

\(x\) = 2 x \(\dfrac{16}{11}\)

\(x\) = \(\dfrac{32}{11}\)

Bài 2: 1 + \(\dfrac{1}{3}\) + \(\dfrac{1}{6}\) + \(\dfrac{1}{10}\) + ... + \(\dfrac{1}{x\left(x+1\right):2}\) = 1 : \(\dfrac{2011}{2012}\)

1 + 2\(\times\) ( \(\dfrac{1}{2\times3}\) + \(\dfrac{1}{2\times6}\) + \(\dfrac{1}{2\times10}\) + ... + \(\dfrac{2}{2\times x\times\left(x+1\right)}\)) = \(\dfrac{2012}{2011}\)

1 + 2 \(\times\)(\(\dfrac{1}{2\times3}\) + \(\dfrac{1}{12}\) + \(\dfrac{1}{20}\)+...+ \(\dfrac{1}{x\times\left(x+1\right)}\)) = \(\dfrac{2012}{2011}\)

1 + 2 \(\times\) (\(\dfrac{1}{2\times3}\) + \(\dfrac{1}{3\times4}\) + ... + \(\dfrac{1}{x\times\left(x+1\right)}\)) = 1 + \(\dfrac{1}{2011}\)

1 + 2\(\times\)(\(\dfrac{1}{2}\) - \(\dfrac{1}{3}\) + \(\dfrac{1}{3}\) - \(\dfrac{1}{4}\) + ... + \(\dfrac{1}{x}\) - \(\dfrac{1}{x+1}\)) = 1 + \(\dfrac{1}{2011}\)

 1 + 2 \(\times\) (\(\dfrac{1}{2}\) - \(\dfrac{1}{x+1}\)) = 1 + \(\dfrac{1}{2011}\)

  1 + 1 - \(\dfrac{2}{x+1}\) = 1 + \(\dfrac{1}{2011}\)

    \(\dfrac{2}{x+1}\) = 1 + 1 - 1  - \(\dfrac{1}{2011}\)

    \(\dfrac{2}{x+1}\) =  2 - 1 - \(\dfrac{1}{2011}\)

  \(\dfrac{2}{x+1}\)  = 1 - \(\dfrac{1}{2011}\)

     \(\dfrac{2}{x+1}\) = \(\dfrac{2010}{2011}\)

       \(x\) + 1 = 2 : \(\dfrac{2010}{2011}\)

        \(x\) + 1 = \(\dfrac{2011}{1005}\)

         \(x\) = \(\dfrac{2011}{1005}\) - 1  = \(\dfrac{1006}{1005}\)(loại vì \(\dfrac{1006}{1005}\) không phải là số tự nhiên)

Vậy không có giá trị nào của \(x\) là số tự nhiên thỏa mãn đề bài. 

Bài 3:

\(\dfrac{x}{16}\) \(\times\) (2017 - 1) = 2

\(\dfrac{x}{16}\) \(\times\) 2016 = 2

 \(\dfrac{x}{16}\)             = 2 : 2016

 \(\dfrac{x}{16}\)            = \(\dfrac{1}{1008}\)

   \(x\)             = \(\dfrac{1}{1008}\) x 16

  \(x\) = \(\dfrac{1}{63}\)

1)

a) \(2x-6=0\)

\(\Leftrightarrow2x=6\)

\(\Leftrightarrow x=3\)

b) \(x\times\left(x+2\right)-3\times\left(x+2\right)=0\)

\(\Leftrightarrow\left(x-3\right)\times\left(x+2\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-3=0\\x+2=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=3\\x=-2\end{cases}}\)

c) \(\frac{x-6}{x+1}=\frac{x^2}{x-1}\)

nhân chéo lên, ngại chết đc

                                                               Bài giải

\(\frac{1}{2}\left(x+1\right)+\frac{1}{4}\left(x+3\right)=3\cdot\frac{1}{3}\cdot\left(x+20\right)\)

\(\frac{1}{2}\left[\left(x+1\right)+\frac{1}{2}\left(x+3\right)\right]=x+20\)

\(\frac{1}{2}\left[x+1+\frac{1}{2}x+\frac{3}{2}\right]=x+20\)

\(\frac{1}{2}\left[x\left(1+\frac{1}{2}\right)+1+\frac{3}{2}\right]=x+20\)

\(\frac{1}{2}\left[\frac{3}{2}x+\frac{5}{2}\right]=x+20\)

\(\frac{3}{4}x+\frac{5}{4}=x+20\)

\(\frac{3}{4}x-x=20-\frac{5}{4}\)

\(\frac{-1}{4}x=\frac{75}{4}\)

\(x=\frac{75}{4}\text{ : }\frac{-1}{4}\)

\(x=-75\)

\(\frac{1}{2}\left(x+1\right)+\frac{1}{4}\left(x+3\right)=3\cdot\frac{1}{3}\cdot\left(x+20\right)\)

\(\frac{1}{2}\left[\left(x+1\right)+\frac{1}{2}\left(x+3\right)\right]=x+20\)

\(\frac{1}{2}\left[x+1+\frac{1}{2}x+\frac{3}{2}\right]=x+20\)

\(\frac{1}{2}\left[x\left(1+\frac{1}{2}\right)+1+\frac{3}{2}\right]=x+20\)

\(\frac{1}{2}\left[\frac{3}{2}x+\frac{5}{2}\right]=x+20\)

\(\frac{3}{4}x+\frac{5}{4}=x+20\)

\(\frac{3}{4}x-x=20-\frac{5}{4}\)

\(\frac{-1}{4}x=\frac{75}{4}\)

\(x=\frac{75}{4}\text{ : }\frac{-1}{4}\)

\(x=-75\)