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8 tháng 6 2015

     x5 - 1/2 * x + 7 * x3 - 2x + 1/5 * x3 + 3 * x4 - x5 + 2/5 + 15 = 23,1

=> (x5 - x5) + (7 * x3 + 1/5 * x3) + (-1/2 * x - 2x) + 3 * x4  + 2/5 + 15 = 23,1

=>      0  +  (36 * x3) /5  + (-5x)/2  +  3 * x4  + 15,4 = 23,1

=>  (36 * x3) /5  + (-5x)/2  +  3 * x4  = 23,1 - 15,4 = 7,7

=> ............

16 tháng 8 2019

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

16 tháng 8 2019

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

Ba bài còn lại tương tự

18 tháng 7 2018

a,x-2/5=5/7

x=5/7+2/5

x=39/35

b,-2/5.x=4/15

x=4/15:-2/5

x=-2/3

18 tháng 7 2018

a) \(x-\frac{2}{5}=\frac{5}{7}\)

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

\(x=\frac{14}{35}+\frac{25}{35}=\frac{39}{35}\)

b)

\(\frac{-2}{5}x=\frac{4}{15}\)

\(x=\frac{4}{15}:-\frac{2}{5}\)

\(x=\frac{4}{15}\cdot-\frac{5}{2}=-\frac{2}{3}\)

c) \(2x\left(x-\frac{1}{7}\right)=2x^2-\frac{2x}{7}\)

d) \(\frac{1}{2}+\frac{3}{4}x=\frac{1}{4}\)

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

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

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

f) \(\frac{11}{12}-\left(\frac{2}{5}+x\right)=\frac{2}{5}\)

\(\frac{2}{5}+x=\frac{11}{12}-\frac{2}{5}=\frac{31}{60}\)

\(x=\frac{31}{60}-\frac{2}{5}=\frac{7}{60}\)

a) \(-12\left(x-5\right)+7\left(3-x\right)=15\)

\(\Leftrightarrow-12x+60+21-7x=15\)

\(\Leftrightarrow-19x=15-\left(60+21\right)=-66\)

\(\Leftrightarrow x=\frac{-66}{-19}=\frac{66}{19}\)

Vậy : \(x=\frac{66}{19}\)

b) \(-\left(2x-3\right)-4\left(x+1\right)=-7x+3\)

\(\Leftrightarrow-2x+3-4x-4=-7x+3\)

\(\Leftrightarrow-2x-4x+7x=3-3+4\)

\(\Leftrightarrow x=4\)

Vậy : \(x=4\)

c) \(-5.\left(x+\frac{1}{5}\right)-\frac{1}{2}.\left(x-\frac{2}{3}\right)=\frac{3}{2}.\frac{-5}{6}\)

\(\Leftrightarrow-5x-1-\frac{1}{2}x+\frac{1}{3}=-\frac{5}{4}\)

\(\Leftrightarrow-\frac{11}{2}x=-\frac{5}{4}+1-\frac{1}{3}=-\frac{7}{12}\)

\(\Leftrightarrow x=-\frac{7}{12}:\frac{-11}{2}=\frac{7}{66}\)

Vậy : \(x=\frac{7}{66}\)

Câu d) Xíu làm mình bận >>

d) \(x-\left\{\left[-x+\left(x+3\right)\right]\right\}-\left[\left(x+3\right)-\left(x-2\right)\right]=0\)

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

\(\Leftrightarrow x+x-x-3-x-3+x-2=0\)

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

\(\Leftrightarrow x+\left(-8\right)=0\)

\(\Leftrightarrow x=8\)

Vậy : \(x=8\)

P/s : Câu này cần chú ý quy tắc chuyển dấu và quy tắc thực hiện khi có dấu ngoặc nhé !

22 tháng 9 2016

oho nhiều quá trời, lm chắc mỏi tay luôn

23 tháng 9 2016

\(\left(\frac{1}{2}\right)^5\times x=\left(\frac{1}{2}\right)^7\) 

              \(x=\left(\frac{1}{2}\right)^7\div\left(\frac{1}{2}\right)^5\)

             \(x=\left(\frac{1}{2}\right)^{7-5}=\left(\frac{1}{2}\right)^2=\frac{1}{4}\) .

\(\left(\frac{3}{7}\right)^2\times x=\left(\frac{9}{21}\right)^2\) 

 \(\left(\frac{3}{7}\right)^2\times x=\left(\frac{3}{7}\right)^4\)            

              \(x=\left(\frac{3}{7}\right)^4\div\left(\frac{3}{7}\right)^2\)

              \(x=\left(\frac{3}{7}\right)^{4-2}=\left(\frac{3}{7}\right)^2=\frac{9}{49}\)

\(2^x=2\Rightarrow x=1\)

\(3^x=3^4\Rightarrow x=4\)

\(7^x=7^7\Rightarrow x=7\)

\(\left(-3\right)^x=\left(-3\right)^5\Rightarrow x=5\)

\(\left(-5\right)^x=\left(-5\right)^4\Rightarrow x=4\)

\(2^x=4\Leftrightarrow2^x=2^2\Rightarrow x=2\)

\(2^x=8\Leftrightarrow2^x=2^3\Rightarrow x=3\)

\(2^x=16\Leftrightarrow2^x=2^4\Rightarrow x=4\)

\(3^{x+1}=3^2\Leftrightarrow x+1=2\Leftrightarrow x=2-1\Rightarrow x=1\)

\(5^{x-1}=5\Leftrightarrow x-1=1\Leftrightarrow x=1+1\Rightarrow x=2\)

\(6^{x+4}=6^{10}\Leftrightarrow x+4=10\Leftrightarrow x=10-4\Rightarrow x=6\)

\(5^{2x-7}=5^{11}\Leftrightarrow2x-7=11\Leftrightarrow2x=11+7\Leftrightarrow2x=18\Leftrightarrow x=18\div2\Rightarrow x=9\)

\(\left(-2\right)^{4x+2}=64\)

\(2^{-4x+2}=2^6\Leftrightarrow-4x+2=6\Leftrightarrow-4x=6-2\Leftrightarrow-4x=4\Leftrightarrow x=4\div\left(-4\right)\Rightarrow x=-1\)

\(\left(\frac{1}{2}\right)^x=\left(\frac{1}{2}\right)^5\Rightarrow x=5\)

\(\left(\frac{5}{6}\right)^{2x}=\left(\frac{5}{6}\right)^5\Rightarrow2x=5\Rightarrow x=\frac{5}{2}\)

\(\left(\frac{3}{4}\right)^{2x-1}=\left(\frac{3}{4}\right)^{5x-4}\Rightarrow2x-1=5x-4\)

                                      \(2x-5x=-4+1\) 

                                           \(-3x=-3\Rightarrow x=1\)

\(\left(\frac{-1}{10}\right)^x=\frac{1}{100}\)

 \(\left(\frac{1}{10}\right)^{-x}=\left(\frac{1}{10}\right)^2\Rightarrow-x=2\Rightarrow x=-2\)

\(\left(\frac{-3}{2}\right)^x=\frac{9}{4}\)

\(\left(\frac{3}{2}\right)^{-x}=\left(\frac{3}{2}\right)^2\Rightarrow-x=2\Rightarrow x=-2\)

\(\left(\frac{-3}{5}\right)^{2x}=\frac{9}{25}\)

 \(\left(\frac{3}{5}\right)^{-2x}=\left(\frac{3}{5}\right)^2\Rightarrow-2x=2\Rightarrow x=-1\)

\(\left(\frac{-2}{3}\right)^x=\frac{-8}{27}\)

\(\left(\frac{-2}{3}\right)^x=\left(\frac{-2}{3}\right)^3\Rightarrow x=3\).

hehe.heheoho đánh tới què tay, hoa mắt lun r nekkk!!hum

20 tháng 8 2015

1) \(\frac{x-1}{x-5}=\frac{6}{7};\left(x-1\right).7=\left(x-5\right).6\)

7x - 7 = 6x - 30 

=> 7x - 6x = -30 - (-7)

x = -23

2) \(\frac{x-1}{3}=\frac{x+3}{5};\left(x-1\right).5=\left(x+3\right).3\)

5x - 5 = 3x + 9

=> 5x - 3x = 9 - (-5)

2x = 14

x = 7

3)  \(\frac{3}{7}=\frac{2x+1}{3x+5};\left(3x+5\right).3=\left(2x+1\right).7\)

9x + 15 = 14x + 7

9x - 14x = 7-15

5x = -8

x = -8/5

4 tháng 4 2018

1) =>\(\hept{\begin{cases}x-1=6\\x-5=7\end{cases}=>\hept{\begin{cases}x=6+1=7\\x=7+5=13\end{cases}}}\)

Vậy x\(\varepsilon\){7;13}

2)

3 tháng 7 2019

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

TH1 : \(\frac{1}{7}x-\frac{2}{7}=0\Rightarrow\frac{x-2}{7}=0\Rightarrow x-2=0\Leftrightarrow x=2\)

TH2 : \(-\frac{1}{5}x+\frac{3}{5}=0\Rightarrow\frac{-x+3}{5}=0\Rightarrow-x+3=0\Leftrightarrow x=3\)

TH3 : \(\frac{1}{3}x+\frac{4}{3}=0\Rightarrow\frac{x+4}{3}=0\Rightarrow x+4=0\Leftrightarrow x=-4\)

\(\Rightarrow x\in\left\{2;3;-4\right\}\)

3 tháng 7 2019

\(b,\frac{1}{6}x+\frac{1}{10}x-\frac{4}{15}x+1=0\)

\(\Rightarrow\frac{5}{30}x+\frac{3}{30}x-\frac{8}{30}x+1=0\)

\(\Rightarrow\frac{5x+3x-8x}{30}+1=0\)

\(\Rightarrow1=0\)( vô lý )\(\Rightarrow x\in\varnothing\)

26 tháng 4 2018

Câu b) tạm thời ko bít làm =.= 

Bài 1 : 

\(d)\) \(\frac{4^5+4^5+4^5+4^5}{3^5+3^5+3^5}.\frac{6^5+6^5+6^5+6^5+6^5+6^5}{2^5+2^5}=2x\)

\(\Leftrightarrow\)\(\frac{4^5.4}{3^5.3}.\frac{6^5.6}{2^5.2}=2x\)

\(\Leftrightarrow\)\(\frac{4^6}{3^6}.\frac{6^6}{2^6}=2x\)

\(\Leftrightarrow\)\(\frac{2^{12}}{3^6}.\frac{2^6.3^6}{2^6}=2x\)

\(\Leftrightarrow\)\(\frac{2^{12}}{3^6}.\frac{3^6}{1}=2x\)

\(\Leftrightarrow\)\(2^{12}=2x\)

\(\Leftrightarrow\)\(x=\frac{2^{12}}{2}\)

\(\Leftrightarrow\)\(x=2^{11}\)

\(\Leftrightarrow\)\(x=2048\)

Vậy \(x=2048\)

Chúc bạn học tốt ~ 

26 tháng 4 2018

Bài 1 : 

\(a)\) Ta có : 

\(4+\frac{x}{7+y}=\frac{4}{7}\)

\(\Leftrightarrow\)\(\frac{x}{7+y}=\frac{4}{7}-4\)

\(\Leftrightarrow\)\(\frac{x}{7+y}=\frac{-24}{7}\)

\(\Leftrightarrow\)\(\frac{x}{-24}=\frac{7+y}{7}\)

Áp dụng tính chất dãy tỉ số bằng nhau ta có : 

\(\frac{x}{-24}=\frac{7+y}{7}=\frac{x+7+y}{-24+7}=\frac{22+7}{-17}=\frac{29}{-17}=\frac{-29}{17}\)

Do đó : 

\(\frac{x}{-24}=\frac{-29}{17}\)\(\Rightarrow\)\(x=\frac{-29}{17}.\left(-24\right)=\frac{696}{17}\)

\(\frac{7+y}{7}=\frac{-29}{17}\)\(\Rightarrow\)\(y=\frac{-29}{17}.7-7=\frac{-322}{17}\)

Vậy \(x=\frac{696}{17}\) và \(y=\frac{-322}{17}\)

Chúc bạn học tốt ~