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cau hoi nao dung day giup toi voi

=> \(\frac{3.5+x}{5}=\frac{3x+7}{5}\Rightarrow3.5+x=3x+7\)

=> 3.5 = 2x + 7 

=> 2x = 15 - 7 = 8

=> x = 8 :  2 = 4

Vậy x = 4

\(\Leftrightarrow\dfrac{x+15}{5}=\dfrac{3x+7}{5}\)

=>3x+7=x+15

=>2x=8

hay x=4

3\(\frac{x}{5}\) = \(\frac{3x+7}{5}\)

Mà 3\(\frac{x}{5}\) =\(\frac{15+x}{5}\)

Suy ra: \(\frac{15+x}{5}\) =\(\frac{3x+7}{5}\)

       15+x=3x+7

      15+x-7=3x+7-7

     8+x=3x

Suy ra: 8=2x

           x=8:2

           x=4

con Thảo giải đúng rồi tick nó đi

3\(\frac{x}{5}\)=\(\frac{15+x}{5}\)

mà 3\(\frac{x}{5}\)=\(\frac{3x+7}{5}\)=>\(\frac{15+x}{5}\)=\(\frac{3x+7}{5}\)

                     =>(15+x)5=(3x+7)5

                     =>15+x=3x+7

                     =>8=2x

                     =>x=8:2

                     =>x=4

Suy ra:(3x-5)*3=4x*2

             9x-15=8x

                   15=9x-8x

                   15=x

Vậy x=15(tick nha)

\(\frac{3.\left(3x-5\right)}{6}=\frac{2.\left(4x\right)}{6}\)

\(3.\left(3x-5\right)=2.4x\)

\(9x-15=8x\)

\(9x-8x=15\)

\(x=15\)

\(\frac{3x-5}{2}=\frac{4x}{3}\Rightarrow3.\left(3x-5\right)=2.4x\Rightarrow9x-15=8x\Rightarrow9x-8x=15\Rightarrow x=15\)

quy đồng \(\frac{3x-5}{2}=\)
\(\frac{3\left(3x-5\right)}{2.3}=\frac{9x-15}{6}\)

\(\frac{4x}{3}=\frac{2.\left(4x\right)}{3.2}=\frac{8x}{6}\)

9x-15=8x

truyển vế đổi đấu 9x-8x=15

x=15

1a) \(\left|\frac{3}{2}x+\frac{1}{2}\right|=\left|4x-1\right|\)

=> \(\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}=4x-1\\\frac{3}{2}x+\frac{1}{2}=1-4x\end{cases}}\)

=> \(\orbr{\begin{cases}-\frac{5}{2}x=-\frac{3}{2}\\\frac{11}{2}x=\frac{1}{2}\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{5}{3}\\x=\frac{1}{11}\end{cases}}\)

b) \(\left|\frac{5}{4}x-\frac{7}{2}\right|-\left|\frac{5}{8}x+\frac{3}{5}\right|=0\)

=>\(\left|\frac{5}{4}x-\frac{7}{2}\right|=\left|\frac{5}{8}x+\frac{3}{5}\right|\)

=> \(\orbr{\begin{cases}\frac{5}{4}x-\frac{7}{2}=\frac{5}{8}x+\frac{3}{5}\\\frac{5}{4}x-\frac{7}{2}=-\frac{5}{8}x-\frac{3}{5}\end{cases}}\)

=> \(\orbr{\begin{cases}\frac{5}{8}x=\frac{41}{10}\\\frac{15}{8}x=\frac{29}{10}\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{164}{25}\\x=\frac{116}{75}\end{cases}}\)

c) TT

a, \(\left|\frac{3}{2}x+\frac{1}{2}\right|=\left|4x-1\right|\)

=> \(\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}=4x-1\\-\frac{3}{2}x-\frac{1}{2}=4x-1\end{cases}}\)

=> \(\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}-4x=-1\\-\frac{3}{2}x-\frac{1}{2}-4x=-1\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{3}{5}\\x=\frac{1}{11}\end{cases}}\)

\(b,\left|\frac{5}{4}x-\frac{7}{2}\right|-\left|\frac{5}{8}x+\frac{3}{5}\right|=0\)

=> \(\left|\frac{5}{4}x-\frac{7}{2}\right|-0=\left|\frac{5}{8}x+\frac{3}{5}\right|\)

=> \(\frac{\left|5x-14\right|}{4}=\frac{\left|25x+24\right|}{40}\)

=> \(\frac{10(\left|5x-14\right|)}{40}=\frac{\left|25x+24\right|}{40}\)

=> \(\left|50x-140\right|=\left|25x+24\right|\)

=> \(\orbr{\begin{cases}50x-140=25x+24\\-50x+140=25x+24\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{164}{25}\\x=\frac{116}{75}\end{cases}}\)

c, \(\left|\frac{7}{5}x+\frac{2}{3}\right|=\left|\frac{4}{3}x-\frac{1}{4}\right|\)

=> \(\orbr{\begin{cases}\frac{7}{5}x+\frac{2}{3}=\frac{4}{3}x-\frac{1}{4}\\-\frac{7}{5}x-\frac{2}{3}=\frac{4}{3}x-\frac{1}{4}\end{cases}}\)

=> \(\orbr{\begin{cases}x=-\frac{55}{4}\\x=-\frac{25}{164}\end{cases}}\)

Bài 2 : a. |2x - 5| = x + 1

 TH1 : 2x - 5 = x + 1

    => 2x - 5 - x = 1

    => 2x - x - 5 = 1

    => 2x - x = 6

    => x = 6

TH2 : -2x + 5 = x + 1

   => -2x + 5 - x = 1

   => -2x - x + 5 = 1

   => -3x = -4

   => x = 4/3

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