1,

\(\dfrac{6}{7}\) + \(\dfrac{-5}{8}\) : (-5) -\(\dfrac{3}{16}\) . \(\left(-2\right)^2\)

= \(\dfrac{6}{7}\) + \(\dfrac{-5}{8}\) . \(\dfrac{-1}{5}\) - \(\dfrac{3}{16}\) . 4

= \(\dfrac{6}{7}\) + \(\dfrac{1}{8}\) - \(\dfrac{3}{4}\)

= \(\dfrac{48}{56}\) + \(\dfrac{7}{56}\) - \(\dfrac{42}{56}\)

= \(\dfrac{13}{56}\)

3,

a,\(\dfrac{3}{5}\)x - \(\dfrac{7}{10}\)x = \(\dfrac{-1}{2}\)

x.(\(\dfrac{3}{5}\) - \(\dfrac{7}{10}\)) = \(\dfrac{-1}{2}\)

x.\(\dfrac{-1}{10}\)= \(\dfrac{-1}{2}\)

x =\(\dfrac{-1}{2}\):\(\dfrac{-1}{10}\)

x = 5

c, (2,5x - 3,6) : \(\dfrac{15}{7}\) = -1

( \(\dfrac{5}{2}\)x - \(\dfrac{18}{5}\)) : \(\dfrac{15}{7}\) = -1

\(\dfrac{5}{2}\)x - \(\dfrac{18}{5}\) = -1 . \(\dfrac{15}{7}\)

\(\dfrac{5}{2}\)x - \(\dfrac{18}{5}\) = \(\dfrac{-15}{7}\)

\(\dfrac{5}{2}\)x = \(\dfrac{-15}{7}\) + \(\dfrac{18}{5}\)

\(\dfrac{5}{2}\)x = \(\dfrac{51}{35}\)

x =\(\dfrac{51}{35}\) : \(\dfrac{5}{2}\)

x = \(\dfrac{102}{175}\)

Mình không biết có chỗ nào sai không nữa.

a, \(x\) : \(\dfrac{13}{3}\) = -2,5

    \(x\)         = -2,5 . \(\dfrac{13}{3}\)

    \(x\)         = \(\dfrac{65}{6}\)

b,\(\dfrac{3}{5}\)\(x\)         = \(\dfrac{1}{10}-\)\(\dfrac{1}{4}\)

   \(\dfrac{3}{5}x\)         = \(\dfrac{-3}{20}\)

      \(x\)          = \(\dfrac{-3}{20}\) :  \(\dfrac{3}{5}\)

      \(x\)          = \(\dfrac{-1}{4}\)

c, \(\dfrac{25}{9}-\dfrac{12}{13}x=\dfrac{7}{9}\)

              \(\dfrac{12}{13}x\)\(=\dfrac{25}{9}-\dfrac{7}{9}\)

               \(\dfrac{12}{13}x=2\)

                    \(x=2:\dfrac{12}{13}\)

                    \(x=\dfrac{13}{6}\)

\(a,\left[0,75x+\frac{5}{2}\right]-\frac{4}{7}-\left[-\frac{1}{3}\right]=-\frac{5}{6}\)

\(\Leftrightarrow\left[0,75x+\frac{5}{2}\right]-\frac{4}{7}+\frac{1}{3}=-\frac{5}{6}\)

\(\Leftrightarrow\left[0,75x+\frac{5}{2}\right]=-\frac{5}{6}-\frac{1}{3}+\frac{4}{7}\)

\(\Leftrightarrow0,75x+\frac{5}{2}=-\frac{25}{42}\)

\(\Leftrightarrow0,75x=-\frac{65}{21}\Leftrightarrow x=-\frac{260}{63}\)

\(b,\left[4x-9\right]\left[2,5+-\frac{7}{3}x\right]=0\)

\(\Leftrightarrow\orbr{\begin{cases}4x-9=0\\2,5+-\frac{7}{3}x=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{9}{4}\\x=\frac{15}{14}\end{cases}}\)

Vậy \(x\in\left\{\frac{9}{4};\frac{15}{14}\right\}\)

Tham khảo nhé phamthiminhanh

a) \(\left(0,75x+\frac{5}{2}\right)-\frac{4}{7}-\left(-\frac{1}{3}\right)=-\frac{5}{6}\)

=>   \(0,75x+\frac{5}{2}-\frac{4}{7}+\frac{1}{3}=-\frac{5}{6}\)

=> \(0,75x=-\frac{5}{6}-\frac{5}{2}+\frac{4}{7}-\frac{1}{3}\)

=>  \(0,75x=-\frac{65}{21}\)

=>   \(x=-\frac{260}{63}\)

b) \(\left(4x-9\right)\left(2,5+-\frac{7}{3}x\right)=0\)

=>   \(10x-\frac{28}{3}x^2-22,5+21x=0\)

=>   \(-\frac{28}{3}x^2+31x-22,5=0\)

=>   Phần còn lại bạn tự giải tiếp nhé!

a: =6-6=0

b: \(=\dfrac{-5}{4}:\dfrac{2-7}{8}+\dfrac{3}{2}\cdot\dfrac{2-5}{6}\)

\(=\dfrac{-5}{4}\cdot\dfrac{8}{-5}+\dfrac{3}{2}\cdot\dfrac{-3}{6}\)

\(=2+\dfrac{-9}{12}=2-\dfrac{3}{4}=\dfrac{5}{4}\)

c: \(=2,5\cdot\left(-0,65\right)+1,5\left(-0,3-0,35\right)=-0,65\cdot4=-2,6\)

_Thần đồng ngu học (Toàn bài dễ)

a) x/7 = 6/21

x/7 = 2/7

=>x=2

b)2/3x -1/2=1/10

2/3x = 1/10+1/2

2/3x = 3/5

x=3/5:2/3

x=9/10

c)1/4+1/3 : x = -5

d)3x+17=2

đ)2/3x +1/4 =7/12

2x+3/10= 11/6 . 6/11

x : 4 1/3 = -2,5

a) x/7 = 6/21

x/7 = 2/7

=>x=2

b)2/3x -1/2=1/10

2/3x = 1/10+1/2

2/3x = 3/5

x=3/5:2/3

x=9/10

c)1/4+1/3 : x = -5

d)3x+17=2

đ)2/3x +1/4 =7/12

2x+3/10= 11/6 . 6/11

x : 4 1/3 = -2,5

1) \(|5x-3|=|7-x|\)

\(\Leftrightarrow\orbr{\begin{cases}5x-3=7-x\\5x-3=x-7\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}6x=10\\4x=-4\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=\frac{5}{3}\\x=-1\end{cases}}\)

Vậy...

2) \(2.|3x-1|-3x=7\)

\(\Leftrightarrow2.|3x-1|=7+3x\)

\(\Leftrightarrow\orbr{\begin{cases}2.\left(3x-1\right)=7+3x\\2.\left(3x-1\right)=-7-3x\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}6x-2=7+3x\\6x-2=-7-3x\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}3x=9\\9x=-5\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=3\\x=\frac{-5}{9}\end{cases}}\)

Vậy...

5) \(\text{1,6 - |x + 1,5| = 0}\)

\(|x + 1,5| = 1,6-0\)

\(\text{|x + 1,5| = 1,6}\)

\( |x | = 1,6-1,5\)

\(|x|=0,1\)

a)  \(\left(\frac{2x}{5}-1\right):\left(-5\right)=\frac{1}{7}\)

\(\frac{2x}{5}-1=\frac{1}{7}.\left(-5\right)\)

\(\frac{2x}{5}-1=\frac{-5}{7}\)

\(\frac{2x}{5}=\frac{-5}{7}+\frac{7}{7}\)

\(\frac{2x}{5}=\frac{2}{7}\)

\(=>2x.7=2.5\)

\(=>14x=10\)

\(=>x=\frac{5}{7}\)

c) \(\left|3,5+2,5x\right|-2,5=3,5\)

\(\left|3,5+2,5x\right|=3,5+2,5\)

\(\left|3,5+2,5x\right|=6\)

\(TH1\)  \(3,5+2,5x=6\)                                        \(TH2\)   \(3,5+2,5x=-6\)

            \(2,5x=6-3,5\)                                                            \(2,5x=-6-3,5\)

             \(2,5x=2,5\)                                                                    \(2,5x=-9.5\)

                    \(x=1\)                                                                    \(x=-3,8\)

     vậy \(x=1\) hoặc  \(x=-3,8\)

câu d) làm tương tự như câu c) 

DÀI QUÁ BẠN Ạ,LÀM ƠN "T I C K" CHO MIK CÁI, THANKS BẠN!

bn ơi ko thì bn làm từng phép một cũng đc nhé các bn giải hộ mình mai mình phải nộp rồi