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4 tháng 8 2016

quá dễ luôn, nhân chéo đi

4 tháng 8 2016

a, <=> 7(37-x)=3(x+13)

<=> x =22

b, <=> (x+1)(x-1)=15

<=> x^2-1=15 <=> x^2=16 <=> x= +_4

11 tháng 4 2019

a) \(\frac{1}{4}+\frac{1}{3}\div\left(2x-1\right)=-5\)

\(\Leftrightarrow\frac{1}{3}\div\left(2x-1\right)=-5-\frac{1}{4}\)

\(\Leftrightarrow\frac{1}{3}\div\left(2x-1\right)=\frac{-20}{4}-\frac{1}{4}\)

\(\Leftrightarrow\frac{1}{3}\div\left(2x-1\right)=\frac{-21}{4}\)

\(\Leftrightarrow\left(2x-1\right)=\frac{1}{3}\div\frac{-21}{4}\)

\(\Leftrightarrow\left(2x-1\right)=\frac{-4}{63}\)

\(\Leftrightarrow2x=\frac{-4}{63}+1\)

\(\Leftrightarrow2x=\frac{-4}{63}+\frac{63}{63}\)

\(\Leftrightarrow2x=\frac{59}{63}\)

\(\Leftrightarrow x=\frac{59}{63}\div2\)

\(\Leftrightarrow x=\frac{59}{126}\)

11 tháng 4 2019

b) \(-\left(5\frac{3}{8}+x-7\frac{5}{24}\right)\div2019\frac{11}{37}=0\)

\(\Leftrightarrow-\left(5\frac{3}{8}+x-7\frac{5}{24}\right)=0.2019\frac{11}{37}\)

\(\Leftrightarrow-5\frac{3}{8}-x+7\frac{5}{24}=0\)

\(\Leftrightarrow\frac{-43}{8}-x+\frac{173}{24}=0\)

\(\Leftrightarrow\frac{-129}{24}-x+\frac{173}{24}=0\)

\(\Leftrightarrow-x+\frac{44}{24}=0\)

\(\Leftrightarrow x=\frac{44}{24}-0\)

\(\Leftrightarrow x=\frac{44}{24}=\frac{11}{6}\)

28 tháng 3 2020

a) ĐKXĐ: x khác +2

\(\frac{x-2}{2+x}-\frac{3}{x-2}-\frac{2\left(x-11\right)}{x^2-4}\)

<=> \(\frac{x-2}{2+x}-\frac{3}{x-2}=\frac{2\left(x-11\right)}{\left(x-2\right)\left(x+2\right)}\)

<=> (x - 2)^2 - 3(2 + x) = 2(x - 11)

<=> x^2 - 4x + 4 - 6 - 3x = 2x - 22

<=> x^2 - 7x - 2 = 2x - 22

<=> x^2 - 7x - 2 - 2x + 22 = 0

<=> x^2 - 9x + 20 = 0

<=> (x - 4)(x - 5) = 0

<=> x - 4 = 0 hoặc x - 5 = 0

<=> x = 4 hoặc x = 5

làm nốt đi 

28 tháng 7 2019

a,  0,4 : x = x : 0,9

<=> x2 = 0,4 . 0,9

<=> x2 = 0,36

<=> x = 0,6 hoặc -0,6

b, \(13\frac{1}{3}\div1\frac{1}{3}=26\div\left(2x-1\right)\)

\(\Leftrightarrow\frac{40}{3}\div\frac{4}{3}=26\div\left(2x-1\right)\)

\(\Leftrightarrow10=26\div\left(2x-1\right)\)

\(\Leftrightarrow2x-1=\frac{13}{5}\)

\(\Leftrightarrow2x=\frac{18}{5}\)

\(\Leftrightarrow x=\frac{9}{5}\)

c, \(0,2\div1\frac{1}{5}=\frac{2}{3}\div\left(6x+7\right)\)

\(\Leftrightarrow\frac{1}{5}\div\frac{6}{5}=\frac{2}{3}\div\left(6x+7\right)\)

\(\Leftrightarrow\frac{1}{6}=\frac{2}{3}\div\left(6x+7\right)\)

\(\Leftrightarrow6x+7=4\)

\(\Leftrightarrow6x=-3\)

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

d, \(\frac{37-x}{x+13}=\frac{3}{7}\) 

\(\Leftrightarrow7\left(37-x\right)=3\left(x+13\right)\)

\(\Leftrightarrow259-7x=3x+39\)

\(\Leftrightarrow-10x=-220\)

\(\Leftrightarrow x=22\)

18 tháng 8 2023

 \(\dfrac{3}{4}\times\dfrac{8}{5}:1\dfrac{1}{6}\) 

=\(\dfrac{6}{5}:\) \(\dfrac{7}{6}\) 

=\(\dfrac{6}{5}\times\dfrac{6}{7}=\dfrac{36}{35}\)

 

2\(\dfrac{1}{3}\) x 1\(\dfrac{1}{4}\) -\(\dfrac{7}{5}\)

\(\dfrac{7}{3}\times\dfrac{5}{4}-\) \(\dfrac{7}{5}\) 

\(\dfrac{35}{12}-\dfrac{7}{5}\)

\(\dfrac{175}{60}-\dfrac{84}{60}=\dfrac{91}{60}\)

 

18 tháng 8 2023

4\(\dfrac{2}{3}+1\dfrac{1}{4} +2\dfrac{1}{3}+2\dfrac{3}{7}\)

(4 +2) + \(\left(\dfrac{2}{3}+\dfrac{1}{3}\right)\) +1\(\dfrac{1}{4}\) + \(2\dfrac{3}{7}\) 

6 + 1 + \(\dfrac{5}{4}\) + \(\dfrac{17}{7}\)

7 + \(\dfrac{103}{28}\)

\(\dfrac{299}{28}\)

11 tháng 7 2017

Ta có : \(\frac{x+1}{5}=\frac{x+2}{6}\)

\(\Rightarrow\left(x+1\right)6=5\left(x+2\right)\)

\(\Leftrightarrow6x+6=5x+10\)

\(\Leftrightarrow6x-5x=10-6\)

\(\Rightarrow x=4\)

27 tháng 11 2017

\(\frac{x+1}{2}\)\(\frac{8}{x+1}\) 

x + 1 . x + 1 = 2 . 8

x . 2             = 16

x                  = 16 : 2

x                  = 8

24 tháng 6 2017

\(\left(\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+....+\frac{1}{19.21}\right).x=\frac{9}{7}\)

\(\left(\frac{5-3}{3.5}+\frac{7-5}{5.7}+\frac{9-7}{7.9}+...+\frac{21-19}{19.21}\right).x=\frac{9}{7}\)

\(\left[\frac{1}{2}.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{19}-\frac{1}{21}\right)\right].x=\frac{9}{7}\)

 \(\left[\frac{1}{2}.\left(\frac{1}{3}-\frac{1}{21}\right)\right].x=\frac{9}{7}\)

 \(\left[\frac{1}{2}.\frac{2}{7}\right].x=\frac{9}{7}\)

\(\frac{1}{7}.x=\frac{9}{7}\)

\(\Rightarrow x=\frac{9}{7}\div\frac{1}{7}=9\)

24 tháng 6 2017

\(\left(\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+...+\frac{1}{19.21}\right)x=\frac{9}{7}\)

\(\Leftrightarrow\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{19}-\frac{1}{21}\right)x=\frac{9}{7}\)

\(\Leftrightarrow\left(\frac{1}{3}-\frac{1}{21}\right)x=\frac{9}{7}\)

\(\Leftrightarrow\frac{2}{7}x=\frac{9}{7}\)

\(\Leftrightarrow x=\frac{9}{2}\)