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a)\(3,8:\left(2x\right)=\dfrac{1}{4}:2\dfrac{2}{3}\)
\(2x=3,8:\dfrac{3}{32}\)
\(x=\dfrac{608}{15}:2\)
\(x=\dfrac{304}{15}\)
b)\(\left(0,25x\right):3=\dfrac{5}{6}:0,125\)
\(0,25x=\dfrac{20}{3}\times3\)
\(x=20:0,25\)
\(x=80\)
c) \(0,01:2,5=\left(0,75\times x\right):0,75\)
\(0,004=0,75\times x:0,75\)
\(0,004=x\times0,75:0,75\)
\(0,004=x\times1\)
\(0,004=x\)
\(\Rightarrow x=0,004\)
d)\(1\dfrac{1}{3}:0,8=\dfrac{2}{3}:\left(0,1x\right)\)
\(\dfrac{5}{3}=\dfrac{2}{3}:0,1\times x\)
\(\dfrac{5}{3}=\dfrac{20}{3}\times x\)
\(\Rightarrow x=\dfrac{20}{3}:\dfrac{5}{3}\)
\(x=4\)
a) \(x=20\dfrac{4}{15}.\)
b) \(x=80\)
c) \(x=0,004\)
d) \(x=4.\)
* Ngoại tỉ :
a) \(-5,1\) và \(-1,15\)
b) \(6\dfrac{1}{2}\) và \(80\dfrac{2}{3}\)
c) \(-0,375\) và \(-3,63\)
* Trung tỉ :
a) \(0,69\) và \(8,5\)
b) \(14\dfrac{2}{3}\) và \(35\dfrac{3}{4}\)
c) \(0,875\) và \(8,47\)
x-5/1+x-5/2+x-5/3+x-5/4=0
=>(x-5)(1+1/2+1/3+1/4)
vì 1+1/2+1/3+1/4 khác 0
=>x-5=0=>x=5
\(\dfrac{9^4.8^6}{6^{10}.16^3}=\dfrac{\left(3^2\right)^4.\left(2^3\right)^6}{3^{10}.2^{10}.\left(2^4\right)^3}=\dfrac{3^8.2^{18}}{3^{10}.2^{22}}=\dfrac{1}{9.4}=\dfrac{1}{36}\)
\(\left(\dfrac{4}{5}x-1\right).\left(6x+\dfrac{1}{2}\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}\dfrac{4}{5}x-1=0\\6x+\dfrac{1}{2}=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}\dfrac{4}{5}x=1\\6x=\dfrac{-1}{2}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{4}\\x=\dfrac{-1}{12}\end{matrix}\right.\)
vậy \(x\in\left\{\dfrac{-1}{12};\dfrac{5}{4}\right\}\)
\(\left(2x+1\right)^2=25\)
\(\left(2x+1\right)^2=\left(\pm5\right)^2\)
\(2x+1=\pm5\)
+)\(2x+1=5\Rightarrow2x=4\Rightarrow x=2\)
+)\(2x+1=-5\Rightarrow2x=-6\Rightarrow x=-3\)
vậy \(x\in\left\{-3;2\right\}\)
\(x:8,5=0,69:\left(-1,15\right)\)
\(\Rightarrow x:8,5=-0,6\)
\(\Rightarrow x=-0,6.8,5=-5,1=\dfrac{-51}{10}\)
vậy \(x=\dfrac{-51}{10}\)
a) Lm r nkoa!
b) \(\left(0,25x\right):3=\frac{5}{6}:0,125\)
\(=\left(0,25x\right):3=\frac{20}{3}\)
\(\Rightarrow0,25x=\frac{20}{3}\cdot3=20\)
\(\Rightarrow x=20:0,25=80\)
\(\Rightarrow x=80\)
c) \(0,01:2,5=\left(0,75x\right):0,75\)
\(=\frac{1}{250}=\left(0,75x\right):0,75\)
\(\Rightarrow0,75x=\frac{1}{250}\cdot0,75=\frac{3}{1000}\)
\(\Rightarrow x=\frac{3}{1000}:0,75=\frac{1}{250}\)
\(\Rightarrow x=\frac{1}{250}\)
d) \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1x\right)\)
\(=\frac{5}{3}=\frac{2}{3}:\left(0,1x\right)\)
\(\Rightarrow0,1x=\frac{2}{3}:\frac{5}{3}=\frac{2}{5}\)
\(\Rightarrow x=\frac{2}{5}:0,1=4\)
\(\Rightarrow4\)
1) a) Ta có: \(\frac{x}{-15}=\frac{-60}{x}\) \(\Rightarrow x^2=\left(-15\right).\left(-60\right)=900\)
\(\Rightarrow x=30\)
b) \(\frac{-2}{x}=\frac{-x}{\frac{8}{25}}\) \(\Rightarrow x.\left(-x\right)=\left(-2\right).\frac{8}{25}\)
\(\Rightarrow x.\left(-x\right)=\frac{-16}{25}\)
\(\Rightarrow x.\left(-x\right)=\left(\frac{-4}{5}\right).\frac{4}{5}\)
Vậy \(x=\frac{4}{5}\)
2) a) \(3,8: \left(2x\right)=\frac{1}{4}:2\frac{2}{3}\)
\(\Rightarrow3,8: \left(2x\right)=\frac{3}{32}\)
\(\Rightarrow2x=\frac{3}{32}:3,8=\frac{15}{608}\)
\(x=\frac{15}{608}:2=\frac{15}{1216}\)
Vậy \(x=\frac{15}{1216}\)
b) \(\left(0,25x\right):3=\frac{5}{6}:0,125\)
\(\Rightarrow\left(0,25x\right):3=\frac{20}{3}\)
\(\Rightarrow0,25x=\frac{20}{3}.3=20\)
\(\Rightarrow x=20:0,25=80\)
Vậy x = 80
c) \(0,01:2,5=\left(0,75x\right):0,75\)
\(\Rightarrow\frac{1}{250}=\left(0,75x\right):0,75\)
\(\Leftrightarrow0,75x=\frac{1}{250}.0,75=\frac{3}{1000}\)
\(\Rightarrow x=\frac{3}{1000}:0,75=\frac{1}{250}\)
Vậy \(x=\frac{1}{250}\)
d) \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1x\right)\)
\(\Rightarrow\frac{5}{3}=\frac{2}{3}:\left(0,1x\right)\)
\(\Rightarrow0,1x=\frac{5}{3}.\frac{2}{3}=\frac{10}{9}\)
\(\Rightarrow x=\frac{10}{9}:0,1=\frac{100}{9}\)
Vậy \(x=\frac{100}{9}\)
a) \(\frac{x}{-15}=\frac{-60}{x}\Leftrightarrow x.x=-15.\left(-60\right)\Leftrightarrow x^2=900\Leftrightarrow x^2=\orbr{\begin{cases}30^2\\\left(-30\right)^2\end{cases}}\Leftrightarrow x=\orbr{\begin{cases}30\\-30\end{cases}}\)
ngoại tỉ: -5,1 và -1,15
trung tỉ: 8,5 và 0,69
ko biết đúng ko, làm đại thôi
a)x:8,5=0,69:(-1,15)
(=)x:8,5=-0,6
(=)x=-0,6.8,5
(=)x=-5,1
Vậy x=-5,1
b) (0,25x):3=4/5:0,125
(=)(0,25x):3=6,4
(=)0,25x=6,4.3
(=)0,25x=19,2
(=)x=19,2:0,25
(=)x=76,8
Vậy x=76,8
a,\(x:8,5=0,69\)
\(x=0,69.8,5\)
\(x=5,865\)
b,\(\left(0,25x\right):3=\dfrac{4}{5}:0,125\)
\(0,25x:3=6,4\)
\(0,25x=19,2\)
\(x=76,8\)