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7 tháng 2 2021
a) Ta có: \(\dfrac{x}{-15}=\dfrac{-60}{x}\)
\(\Leftrightarrow x^2=\left(-15\right)\cdot\left(-60\right)=900\)
hay \(x\in\left\{30;-30\right\}\)
Vậy: \(x\in\left\{30;-30\right\}\)
b) Ta có: \(\left|x\right|+0.573=2\)
\(\Leftrightarrow\left|x\right|=1.427\)
hay \(x\in\left\{1.427;-1.427\right\}\)
Vậy: \(x\in\left\{1.427;-1.427\right\}\)
c) Ta có: \(\left|x+\dfrac{1}{3}\right|-4=-1\)
\(\Leftrightarrow\left|x+\dfrac{1}{3}\right|=3\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{3}=3\\x+\dfrac{1}{3}=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{8}{3}\\x=-\dfrac{10}{3}\end{matrix}\right.\)
Vậy: \(x\in\left\{\dfrac{8}{3};-\dfrac{10}{3}\right\}\)
d) Ta có: \(0.01:2.5=\left(0.75x\right):0.75\)
\(\Leftrightarrow\dfrac{0.75\cdot x}{0.75}=\dfrac{0.01}{2.5}\)
\(\Leftrightarrow x=\dfrac{1}{250}\)
Vậy: \(x=\dfrac{1}{250}\)
TP
16 tháng 7 2017
a, 2 -|3/2x -1/4| =|-1,25 |
=>2 -|3/2x-1/4 | = 1,25
=> |3/2x -1/4| = 2-1,25
=> 3/2x -1/4 = 0,75 hoac 3/2x -1/4 = -0,75
=> 3/2 x = 3/4 -1/4 hoac 3/2 x = -3/4 -1/4
=> 3/2 x = 1/2 hoac 3/2 x = -1
=> x = 1/2 :3/2 hoac x = -1 : 3/2
=> x = 1/3 hoac x = -2/3
vay
PP
16 tháng 7 2017
cảm ơn nhé nhưng mk bt làm òi
mk chỉ đăng câu hỏi cho vv thui
23 tháng 7 2020
Bài làm:
1) \(\frac{3}{5}\div\frac{2x}{15}=\frac{1}{2}\div\frac{4}{5}\)
\(\Leftrightarrow\frac{9}{2x}=\frac{5}{8}\)
\(\Rightarrow10x=72\)
\(\Leftrightarrow x=\frac{36}{5}\)
2) \(-\frac{4}{2,5}\div\frac{3}{5}=\frac{1}{5}\div x\)
\(\Leftrightarrow\frac{1}{5}\div x=-\frac{8}{3}\)
\(\Rightarrow x=-\frac{3}{40}\)
3) \(0,12\div3=2x\div\frac{3}{5}\)
\(\Leftrightarrow\frac{1}{25}=\frac{10}{3}x\)
\(\Rightarrow x=\frac{3}{250}\)
29 tháng 10 2017
a) \(\dfrac{1,2}{x+3}=\dfrac{5}{4}\)
\(\Rightarrow\left(x+3\right).5=1,2.4\)
\(\Rightarrow\left(x+3\right).5=4,8\)
\(\Rightarrow x+3=4,8:5\)
\(\Rightarrow x+3=0,96\)
\(\Rightarrow x=-2,04\)
vậy \(x=-2,04\)
b)\(\dfrac{3}{5}:\dfrac{2x}{15}=\dfrac{1}{2}:\dfrac{4}{5}\)
\(\Rightarrow\dfrac{3}{5}:\dfrac{2x}{15}=\dfrac{5}{8}\)
\(\Rightarrow\dfrac{2x}{15}=\dfrac{3}{5}:\dfrac{5}{8}\)
\(\Rightarrow\dfrac{2x}{15}=\dfrac{24}{25}\)
\(\Rightarrow15.24=\left(2x\right).25\)
\(\Rightarrow360=\left(2x\right).25\)
\(\Rightarrow360:25=2x\)
\(\Rightarrow14,4=2x\)
\(\Rightarrow x=7,2\)
vậy \(x=7,2\)
29 tháng 10 2017
\(a,\dfrac{1,2}{x+3}=\dfrac{5}{4}\\ \left(x+3\right).5=1,2.4\\ 5x+8=4,8\\ 5x=4,8-8\\ 5x=-3,2\\ x=-3,2:5=-0,64\)
\(b,\dfrac{3}{5}:\dfrac{2x}{15}=\dfrac{1}{2}:\dfrac{4}{5}\\ \dfrac{2x}{15}=\dfrac{3}{5}\cdot\dfrac{4}{5}:\dfrac{1}{2}\\ \dfrac{2x}{15}=\dfrac{12}{25}.2\\ \dfrac{2x}{25}=\dfrac{24}{25}\\ 2x=\dfrac{24}{25}.5\\ 2x=\dfrac{24}{5}\\ x=\dfrac{24}{5}\cdot\dfrac{1}{2}=\dfrac{12}{5}\)
\(c,-\dfrac{4}{2,5}:3,5=1,5:x\\ x=3,5.1,5:\left(-\dfrac{4}{25}\right)\\ x=\dfrac{21}{4}\cdot\left(-\dfrac{25}{4}\right)=-\dfrac{525}{16}\)
\(d,0,12:3=2x:\dfrac{3}{5}\\ 2x=0,12\cdot\dfrac{3}{5}:3\\ 2x=\dfrac{9}{125}\cdot\dfrac{1}{3}\\ 2x=\dfrac{3}{125}\\ x=\dfrac{3}{125}\cdot\dfrac{1}{2}=\dfrac{3}{250}\)
\(\dfrac{15}{4}-2,5:\left|\dfrac{3}{4}.x+\dfrac{1}{2}\right|=3\)
\(\Rightarrow2,5:\left|\dfrac{3}{4}.x+\dfrac{1}{2}\right|=\dfrac{15}{4}-3\)
\(\Rightarrow2,5:\left|\dfrac{3}{4}.x+\dfrac{1}{2}\right|=\dfrac{3}{4}\)
\(\Rightarrow\left|\dfrac{3}{4}x+\dfrac{1}{2}\right|=2,5:\dfrac{3}{4}\)
\(\Rightarrow\left|\dfrac{3}{4}x+\dfrac{1}{2}\right|=\dfrac{10}{3}\)
\(\Rightarrow\left[{}\begin{matrix}\dfrac{3}{4}x+\dfrac{1}{2}=\dfrac{10}{3}\\\dfrac{3}{4}x+\dfrac{1}{2}=-\dfrac{10}{3}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}\dfrac{3}{4}x=\dfrac{17}{6}\\\dfrac{3}{4}x=\dfrac{-23}{6}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=\dfrac{34}{9}\\x=\dfrac{-46}{9}\end{matrix}\right.\)
Vậy............