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12 tháng 5

x = 3

\(\dfrac{6}{x}=\dfrac{10}{5}\)

=>\(x=6\cdot\dfrac{5}{10}\)

=>\(x=\dfrac{30}{10}=3\)

13 tháng 7 2019

a,  3^9:3^2=3^7

b,  (3/5)^15:(3/5)^10=(3/5)^5

c,  (5.3.3)^10.5^10 / (5.5.3)^10=5^10.3^10.3^10.5^10 / 5^10.5^10.3^10=5^20.3^20 / 5^20.3^10=3^10

23 tháng 10 2021

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

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

\(\Rightarrow x=\frac{6}{-5}\)

Vậy chọn B

26 tháng 11 2021

\(x^2=1\Rightarrow\left[{}\begin{matrix}x=-1\\x=1\end{matrix}\right.\)

\(x^2=3\Rightarrow\left[{}\begin{matrix}x=-\sqrt{3}\\x=\sqrt{3}\end{matrix}\right.\)

\(x^2=5\Rightarrow\left[{}\begin{matrix}x=-\sqrt{5}\\x=\sqrt{5}\end{matrix}\right.\Rightarrow x=-\sqrt{5}\left(vì.x< 0\right)\)

\(x^2=7\Rightarrow\left[{}\begin{matrix}x=-\sqrt{7}\\x=\sqrt{7}\end{matrix}\right.\Rightarrow x=-\sqrt{7}\left(vì.x< 0\right)\)

\(x^2=9\Rightarrow\left[{}\begin{matrix}x=-3\\x=3\end{matrix}\right.\)

\(\left(x-2\right)^2=2\Rightarrow\left[{}\begin{matrix}x-2=-\sqrt{2}\\x-2=\sqrt{2}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=2-\sqrt{2}\\x=2+\sqrt{2}\end{matrix}\right.\)

\(\left(x-4\right)^2=4\Rightarrow\left[{}\begin{matrix}x-2=-2\\x-2=2\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=4\end{matrix}\right.\)

\(\left(x-6\right)^2=6\Rightarrow\left[{}\begin{matrix}x-6=-\sqrt{6}\\x-6=\sqrt{6}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=6-\sqrt{6}\\x=6+\sqrt{6}\end{matrix}\right.\)

\(\left(x-8\right)^2=8\Rightarrow\left[{}\begin{matrix}x-8=-2\sqrt{2}\\x-8=2\sqrt{2}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=8-2\sqrt{2}\\x=2+2\sqrt{2}\end{matrix}\right.\)

\(\left(x-10\right)^2=10\Rightarrow\left[{}\begin{matrix}x-10=-\sqrt{10}\\x-10=\sqrt{10}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=10-\sqrt{10}\\x=10+\sqrt{10}\end{matrix}\right.\)

\(\left(x-\sqrt{3}\right)^2=3\Rightarrow\left[{}\begin{matrix}x-\sqrt{3}=-\sqrt{3}\\x-\sqrt{3}=\sqrt{3}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=2\sqrt{3}\end{matrix}\right.\)

\(\left(x-\sqrt{5}\right)^2=5\Rightarrow\left[{}\begin{matrix}x-\sqrt{5}=-\sqrt{5}\\x-\sqrt{5}=\sqrt{5}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=2\sqrt{5}\end{matrix}\right.\)

12 tháng 4 2018

E = x^(4)*y^(4)+x^(5)*y^(5)+x^(6)*y^(6)+x^(7)*y^(7)+x^(8)*y^(8)+x^(9)*y^(9)+x^(10)*y^(10) tại x=-1, y=1 nha

b) Ta có: \(5^{x+4}-3\cdot5^{x+3}=2\cdot5^{11}\)

\(\Leftrightarrow2\cdot5^{x+3}=2\cdot5^{11}\)

\(\Leftrightarrow x+3=11\)

hay x=8

c) Ta có: \(2\cdot3^{x+2}+4\cdot3^{x+1}=10\cdot3^6\)

\(\Leftrightarrow18\cdot3^x+12\cdot3^x=10\cdot3^6\)

\(\Leftrightarrow30\cdot3^x=30\cdot3^5\)

Suy ra: x=5

d) Ta có: \(6\cdot8^{x-1}+8^{x+1}=6\cdot8^{19}+8^{21}\)

\(\Leftrightarrow6\cdot\dfrac{8^x}{8}+8^x\cdot8=6\cdot8^{19}+64\cdot8^{19}\)

\(\Leftrightarrow8^x\cdot\dfrac{35}{4}=70\cdot8^{19}\)

\(\Leftrightarrow8^x=8^{20}\)

Suy ra: x=20

18 tháng 9 2020

\(x-\frac{3}{8}=\frac{1}{6}-\frac{1}{5}\)

=> \(x-\frac{3}{8}=\frac{5}{30}-\frac{6}{30}=-\frac{1}{30}\)

=> \(x=-\frac{1}{30}+\frac{3}{8}\)

=> \(x=\frac{41}{120}\)

\(-\frac{7}{10}\left(x+\frac{1}{3}\right)=\frac{4}{5}\)

=> \(-\frac{7}{10}x-\frac{7}{30}=\frac{4}{5}\)

=> \(-\frac{7}{10}x=\frac{4}{5}+\frac{7}{30}=\frac{31}{30}\)

=> \(x=\frac{31}{30}:\left(-\frac{7}{10}\right)=\frac{31}{30}\cdot\left(-\frac{10}{7}\right)=-\frac{31}{21}\)

\(x-\frac{4}{3}=\frac{5}{6}\Rightarrow x=\frac{5}{6}+\frac{4}{3}=\frac{5}{6}+\frac{8}{6}=\frac{13}{6}\)

Thiếu đề 

\(\frac{6}{5}+\left(x-\frac{2}{3}\right)=\frac{4}{7}\)

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

=> \(\frac{6}{5}+x=\frac{4}{7}+\frac{2}{3}=\frac{26}{21}\)

=> \(x=\frac{26}{21}-\frac{6}{5}=\frac{4}{105}\)

2 tháng 8 2023

\(\dfrac{1}{5}\times x-\dfrac{2}{3}=\dfrac{1}{10}\times x+\dfrac{5}{6}\)

\(\dfrac{1}{5}x-\dfrac{2}{3}-\dfrac{1}{10}x-\dfrac{5}{6}=0\)

\(\dfrac{1}{5}x-\dfrac{1}{10}x-\dfrac{2}{3}-\dfrac{5}{6}=0\)

\(\dfrac{1}{10}x-\dfrac{3}{2}=0\)

\(\dfrac{1}{10}x=\dfrac{3}{2}\)

\(x=15\)

2 tháng 8 2023

           \(\dfrac{1}{5}\).x - \(\dfrac{2}{3}\) = \(\dfrac{1}{10}\).x + \(\dfrac{5}{6}\)

⇒   \(\dfrac{1}{5}\).x - \(\dfrac{1}{10}\).x = \(\dfrac{5}{6}\) + \(\dfrac{2}{3}\)

⇒ \(\dfrac{2}{10}\).x - \(\dfrac{1}{10}\).x = \(\dfrac{5}{6}\) + \(\dfrac{4}{6}\)

⇒            \(\dfrac{1}{10}\).x = \(\dfrac{9}{6}\)

⇒                  x = \(\dfrac{9}{6}\) : \(\dfrac{1}{10}\)

⇒                  x = \(\dfrac{9}{6}\) . 10

⇒                  x = \(\dfrac{90}{6}\)

⇒                  x = 15

       Vậy x = 15

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

\(\Leftrightarrow-5(5-2x)=3\left(4x-1\right)\)

\(\Leftrightarrow10x-25=12x-3\)

\(\Leftrightarrow10x-12x=25-3\)

\(\Leftrightarrow-2x=22\)

\(\Leftrightarrow x=-11\)

b,  \(\frac{\left(12-3x\right)}{32}=\frac{6}{\left(4-x\right)}\)

\(\Leftrightarrow\frac{3\left(4-x\right)}{32}=\frac{6}{\left(4-x\right)}\)

\(\Leftrightarrow3(4-x)\left(4-x\right)=32.6\)

\(\Leftrightarrow(4-x)\left(4-x\right)=32.2\)

\(\Leftrightarrow(4-x)^2=64\)

\(\Leftrightarrow\orbr{\begin{cases}4-x=8\\4-x=-8\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=-4\\x=12\end{cases}}\)

c,  \(\frac{\left(10-2x\right)}{6}=\frac{27}{\left(5-x\right)}\)

\(\Leftrightarrow\frac{2\left(5-x\right)}{6}=\frac{27}{\left(5-x\right)}\)

\(\Leftrightarrow2(5-x)\left(5-x\right)=27.6\)

\(\Leftrightarrow(5-x)\left(5-x\right)=27.3\)

\(\Leftrightarrow(5-x)^2=81\)

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

\(\Leftrightarrow\orbr{\begin{cases}x=-4\\x=14\end{cases}}\)

1 tháng 10 2020

a, \(\frac{5-2x}{3}=\frac{4x-1}{-5}\Leftrightarrow-25+10x=12x-3\Leftrightarrow-22-2x=0\Leftrightarrow x=-11\)

b, \(\frac{12-3x}{32}=\frac{6}{4-x}\Leftrightarrow\frac{12-3x}{32}=\frac{18}{12-3x}\)

\(\Leftrightarrow\left(12-3x\right)^2=576\Leftrightarrow12-3x=\pm2\)\(\Leftrightarrow\orbr{\begin{cases}x=\frac{10}{3}\\x=\frac{14}{3}\end{cases}}\)

c, \(\frac{10-2x}{6}=\frac{27}{5-x}\Leftrightarrow\frac{10-2x}{6}=\frac{54}{10-2x}\)

\(\Leftrightarrow\left(10-2x\right)^2=324\Leftrightarrow10-2x=\pm18\)\(\Leftrightarrow\orbr{\begin{cases}x=14\\x=-4\end{cases}}\)