Có lẽ bạn viết đề sai.

Câu hỏi của Vũ Mai Linh - Toán lớp 7 - Học toán với OnlineMath

mik viết đề đúng mà sai chỗ nào vayh

      \(\frac{x+2}{327}+\frac{x+3}{326}+\frac{x+4}{325}+\frac{x+5}{324}+\frac{x+349}{5}=0\)

\(\Leftrightarrow\)\(\frac{x+2}{327}+1+\frac{x+3}{326}+1+\frac{x+4}{325}+1+\frac{x+5}{324}+1 +\frac{x+349}{5}-4=0\)

\(\Leftrightarrow\)\(\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}+\frac{x+329}{5}=0\)

\(\Leftrightarrow\)\(\left(x+329\right)\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)=0\)

\(\Leftrightarrow\)\(x+329=0\)   (vì  1/327 + 1/326 + 1/325 + 1/324 + 1/5  khác  0  )

\(\Leftrightarrow\)\(x=-329\)

Bài 1 : 

\(\frac{x+2}{327}+\frac{x+3}{326}+\frac{x+4}{325}+\frac{x+5}{324}+\frac{x+349}{5}=0\)

\(\Leftrightarrow\)\(\left(\frac{x+2}{327}+1\right)+\left(\frac{x+3}{326}+1\right)+\left(\frac{x+4}{325}+1\right)+\left(\frac{x+5}{324}+1\right)+\left(\frac{x+349}{5}-4\right)=0\)

\(\Leftrightarrow\)\(\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}+\frac{x+329}{5}=0\)

\(\Leftrightarrow\)\(\left(x+329\right)\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)=0\)

Vì \(\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)\ne0\)

\(\Rightarrow\)\(x+329=0\)

\(\Rightarrow\)\(x=-329\)

Vậy \(x=-329\)

1. 0,4x - 1/5x = 3/4

=> 1/5x = 3/4

=> x = 3/4 : 1/5

=> x = 15/4

2.

x : 1 2/7 = -3,5

=> x = -3,5 . 9/7 

=> x = -9/2

d,

\(|x-\frac{1}{3}|=\frac{5}{6}\Rightarrow \left[\begin{matrix} x-\frac{1}{3}=\frac{5}{6}\\ x-\frac{1}{3}=-\frac{5}{6}\end{matrix}\right.\Leftrightarrow \left[\begin{matrix} x=\frac{7}{6}\\ x=\frac{-1}{2}\end{matrix}\right.\)

e,

\(\frac{3}{4}-2|2x-\frac{2}{3}|=2\)

\(\Leftrightarrow 2|2x-\frac{2}{3}|=\frac{3}{4}-2=\frac{-5}{4}\)

\(\Leftrightarrow |2x-\frac{2}{3}|=-\frac{5}{8}<0\) (vô lý vì trị tuyệt đối của 1 số luôn không âm)

Vậy không tồn tại $x$ thỏa mãn đề bài.

f, 

\(\frac{2x-1}{2}=\frac{5+3x}{3}\Leftrightarrow 3(2x-1)=2(5+3x)\)

\(\Leftrightarrow 6x-3=10+6x\)

\(\Leftrightarrow 13=0\) (vô lý)

Vậy không tồn tại $x$ thỏa mãn đề bài.

a,

$0-|x+1|=5$

$|x+1|=0-5=-5<0$ (vô lý do trị tuyệt đối của một số luôn không âm)

Do đó không tồn tại $x$ thỏa mãn điều kiện đề.

b,

\(2-|\frac{3}{4}-x|=\frac{7}{12}\)

\(|\frac{3}{4}-x|=2-\frac{7}{12}=\frac{17}{12}\)

\(\Rightarrow \left[\begin{matrix} \frac{3}{4}-x=\frac{17}{12}\\ \frac{3}{4}-x=\frac{-17}{12}\end{matrix}\right.\Rightarrow \left[\begin{matrix} x=\frac{-2}{3}\\ x=\frac{13}{6}\end{matrix}\right.\)

c, 

\(2|\frac{1}{2}x-\frac{1}{3}|-\frac{3}{2}=\frac{1}{4}\)

\(2|\frac{1}{2}x-\frac{1}{3}|=\frac{7}{4}\)

\(|\frac{1}{2}x-\frac{1}{3}|=\frac{7}{8}\)

\(\Rightarrow \left[\begin{matrix} \frac{1}{2}x-\frac{1}{3}=\frac{7}{8}\\ \frac{1}{2}x-\frac{1}{3}=-\frac{7}{8}\end{matrix}\right.\Rightarrow \left[\begin{matrix} x=\frac{29}{12}\\ x=\frac{-13}{12}\end{matrix}\right.\)

a: 0-|x+1|=5

=>|x+1|=0-5=-5<0(vô lý)

=>x∈∅

b: \(2-\left|\frac34-x\right|=\frac{7}{12}\)

=>\(\left|x-\frac34\right|=2-\frac{7}{12}=\frac{17}{12}\)

=>\(\left[\begin{array}{l}x-\frac34=\frac{17}{12}\\ x-\frac34=-\frac{17}{12}\end{array}\right.\Rightarrow\left[\begin{array}{l}x=\frac{17}{12}+\frac{9}{12}=\frac{26}{12}=\frac{13}{6}\\ x=-\frac{17}{12}+\frac34=-\frac{17}{12}+\frac{9}{12}=-\frac{8}{12}=-\frac23\end{array}\right.\)

c: \(2\left|\frac12x-\frac13\right|-\frac32=\frac14\)

=>\(\left|2\left(\frac12x-\frac13\right)\right|=\frac32+\frac14=\frac74\)

=>\(\left|x-\frac23\right|=\frac74\)

=>\(\left[\begin{array}{l}x-\frac23=\frac74\\ x-\frac23=-\frac74\end{array}\right.\Rightarrow\left[\begin{array}{l}x=\frac74+\frac23=\frac{21+8}{12}=\frac{29}{12}\\ x=-\frac74+\frac23=\frac{-21+8}{12}=-\frac{13}{12}\end{array}\right.\)

d: \(\left|x-\frac13\right|=\frac56\)

=>\(\left[\begin{array}{l}x-\frac13=\frac56\\ x-\frac13=-\frac56\end{array}\right.\Rightarrow\left[\begin{array}{l}x=\frac56+\frac13=\frac76\\ x=-\frac56+\frac13=-\frac36=-\frac12\end{array}\right.\)

e: \(\frac34-2\left|2x-\frac23\right|=2\)

=>\(2\left|2x-\frac23\right|=\frac34-2=-\frac54<0\) (vô lý)

=>x∈∅

f: \(\frac{2x-1}{2}=\frac{5+3x}{3}\)

=>3(2x-1)=2(3x+5)

=>6x-3=6x+10

=>-3=10(vô lý)

=>x∈∅

$\textbf{a)}$

$\dfrac{x-1}{2}+\dfrac{x-2}{5}=\dfrac14+\dfrac{x-7}{10}$

$\Leftrightarrow\dfrac{5(x-1)+2(x-2)}{10}=\dfrac14+\dfrac{x-7}{10}$

$\Leftrightarrow\dfrac{7x-9}{10}=\dfrac14+\dfrac{x-7}{10}$

$\Leftrightarrow14x-18=5+2x-14$

$\Leftrightarrow12x=9$

$\Leftrightarrow x=\dfrac34.$

$\textbf{b)}$

$\dfrac{3-2}{2x-3}=\dfrac25+\dfrac1{2x-3}-\dfrac32$

$\Leftrightarrow1-\dfrac2{2x-3}=-\dfrac{11}{10}+\dfrac1{2x-3}$

$\Leftrightarrow\dfrac{21}{10}=\dfrac3{2x-3}$

$\Leftrightarrow21(2x-3)=30$

$\Leftrightarrow42x=93$

$\Leftrightarrow x=\dfrac{31}{14}.$

\(\frac{24}{-12}\) = \(\frac{x}{5}\) = \(\frac{-y}{3}\)

- 2 = \(\frac{x}{5}\) = \(\frac{-y}{3}\)

\(x=5.\left(-2\right)\) = -10

y = -2.3:(-1) = -6:(-1) = 6

Vậy (\(x;y\)) = (-10; 6)

 a) bn nhân chéo lên rồi tính sau đó cho x sang 1 bên và đc x =1

b) x=1 ; y=-1 ; z= -2

c) x= 1,75

d) x=2 bởi vì cũng nhân chéo lên sẽ là ( x+ 2)^2 = 4^2 suy ra x+2 = 4

e) (x-1)^2 = -20 . 5 = -100 suy ra k có x thoa mãn

a)  5(x+1)= 2(2x+3)

     5x+5=4x+6

     5x-4x=6-5

       x      =1

c)4(x-2)=4(5-3x)

   4x-8= 20-12x

4x+12x=8+20

16x= 28

  x= 28/16

x=1,75

d) (x+2)(x+2)=4x4

       (x+2)²  =4²

         x+2=4 hoặc x+2=-4

         x=2                 x=-6

e) (x-1)(x-1)=(-20)x 5

        (x-1)² = -100

 suy ra: k^o  có x thỏa mãn 

Mình đang cần gắp 

bạn còn

chỉ có một số \(\frac{-3}{4}\) thôi nha

ĐKXXD : \(x\ne20;8;3;1\)

\(\frac{2}{\left(x-1\right)\left(x-3\right)}+\frac{5}{\left(x-3\right)\left(x-8\right)}+\frac{12}{\left(x-8\right)\left(x-20\right)}-\frac{1}{x-20}=-\frac{3}{4}\)

\(\Leftrightarrow\frac{\left(x-1\right)-\left(x-3\right)}{\left(x-1\right)\left(x-3\right)}+\frac{\left(x-3\right)-\left(x-8\right)}{\left(x-3\right)\left(x-8\right)}+\frac{\left(x-8\right)-\left(x-20\right)}{\left(x-8\right)\left(x-20\right)}-\frac{1}{x-20}=-\frac{3}{4}\)

\(\Leftrightarrow\frac{1}{x-3}-\frac{1}{x-1}+\frac{1}{x-8}-\frac{1}{x-3}+\frac{1}{x-20}-\frac{1}{x-8}+\frac{1}{x-20}=-\frac{3}{4}\)

\(\Leftrightarrow-\frac{1}{x-1}=-\frac{3}{4}\Leftrightarrow x-1=\frac{4}{3}\Rightarrow x=\frac{7}{3}\)