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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, \(\frac{37-x}{x+13}=\frac{3}{7}\)
\(\Leftrightarrow7\left(37-x\right)=3\left(x+13\right)\)
\(\Leftrightarrow259-7x=3x+39\)
\(\Leftrightarrow-10x=-220\)
\(\Leftrightarrow x=22\)
a) 0,4:x=x:0,9
0,4.0,9=x2
0,36 =x2
\(\sqrt{0,36}\)=x
0,6 =x
a) 0,4 : x = x : 0,9
x2 = 0,4 . 0,9
x2 = \(\frac{9}{25}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{3}{5}\\x=\frac{-3}{5}\end{cases}}\)
b) \(13\frac{1}{3}:1\frac{1}{3}=26:\left(2x-1\right)\)
26 : ( 2x - 1 ) = 10
2x - 1 = \(\frac{13}{5}\)
\(\Rightarrow x=\frac{9}{5}\)
c) 0,2 : \(1\frac{1}{5}=\frac{2}{3}:\left(6x+7\right)\)
\(\frac{1}{6}=\frac{2}{3}:\left(6x+7\right)\)
\(6x+7=4\)
\(\Rightarrow x=\frac{-1}{2}\)
a)
\(\begin{array}{l}\frac{2}{9}:x + \frac{5}{6} = 0,5\\\frac{2}{9}:x = \frac{1}{2} - \frac{5}{6}\\\frac{2}{9}:x = \frac{3}{6} - \frac{5}{6}\\\frac{2}{9}:x = \frac{{ - 2}}{6}\\x = \frac{2}{9}:\frac{{ - 2}}{6}\\x = \frac{2}{9}.\frac{{ - 6}}{2}\\x = \frac{{ - 2}}{3}\end{array}\)
Vậy \(x = \frac{{ - 2}}{3}\).
b)
\(\begin{array}{l}\frac{3}{4} - \left( {x - \frac{2}{3}} \right) = 1\frac{1}{3}\\x - \frac{2}{3} = \frac{3}{4} - 1\frac{1}{3}\\x - \frac{2}{3} = \frac{3}{4} - \frac{4}{3}\\x - \frac{2}{3} = \frac{9}{{12}} - \frac{{16}}{{12}}\\x - \frac{2}{3} = \frac{{ - 7}}{{12}}\\x = \frac{{ - 7}}{{12}} + \frac{2}{3}\\x = \frac{{ - 7}}{{12}} + \frac{8}{{12}}\\x = \frac{1}{12}\end{array}\)
Vậy\(x = \frac{1}{12}\).
c)
\(\begin{array}{l}1\frac{1}{4}:\left( {x - \frac{2}{3}} \right) = 0,75\\\frac{5}{4}:\left( {x - \frac{2}{3}} \right) = \frac{3}{4}\\x - \frac{2}{3} = \frac{5}{4}:\frac{3}{4}\\x - \frac{2}{3} = \frac{5}{4}.\frac{4}{3}\\x - \frac{2}{3} = \frac{5}{3}\\x = \frac{5}{3} + \frac{2}{3}\\x = \frac{7}{3}\end{array}\)
Vậy \(x = \frac{7}{3}\).
d)
\(\begin{array}{l}\left( { - \frac{5}{6}x + \frac{5}{4}} \right):\frac{3}{2} = \frac{4}{3}\\ - \frac{5}{6}x + \frac{5}{4} = \frac{4}{3}.\frac{3}{2}\\ - \frac{5}{6}x + \frac{5}{4} = 2\\ - \frac{5}{6}x = 2 - \frac{5}{4}\\ - \frac{5}{6}x = \frac{8}{4} - \frac{5}{4}\\ - \frac{5}{6}x = \frac{3}{4}\\x = \frac{3}{4}:\left( { - \frac{5}{6}} \right)\\x = \frac{3}{4}.\frac{{ - 6}}{5}\\x = \frac{{ - 9}}{{10}}\end{array}\)
Vậy \(x = \frac{{ - 9}}{{10}}\).
a)\(0,2:1\frac{1}{5}=\frac{2}{3}:\left(6.x+7\right)\)
\(\frac{2}{3}:\left(6.x+7\right)=0,2:1\frac{1}{5}\)
\(\frac{2}{3}:\left(6.x+7\right)=0,2:\frac{6}{5}\)
\(\frac{2}{3}:\left(6.x+7\right)=\frac{1}{6}\)
\(6.x+7=\frac{2}{3}:\frac{1}{6}\)
\(6.x+7=4\)
\(6.x=4-7\)
\(6.x=-3\)
\(x=-3:6\)
\(x=-0,5\)
Vậy x=-0,5 hay \(\frac{-1}{2}\)
d)\(\frac{x}{y}=\frac{2}{3};x.y=96\)
Từ \(\frac{x}{y}=\frac{2}{3}\)suy ra \(\frac{x}{3}=\frac{y}{2}\)
Đặt k=\(\frac{x}{3}=\frac{y}{2}\)
\(\Rightarrow x=3.k;y=2.k\)
Vì \(x.y=96\)nên \(2k.3k=96\)
\(\Rightarrow6.k^2=96\)
\(\Rightarrow k^2=96:6\)
\(\Rightarrow k^2=16\)
\(\Rightarrow k=4\)hoặc\(k=-4\)
+)Với \(k=4\)thì \(x=2\);\(y=3\)
+)Với \(k=-4\)thì \(x=-2\);\(y=-3\)
Vậy \(x=2;y=3\)hoặc \(x=-2;y=-3\)
e) \(\frac{x}{2}=\frac{y}{3}=\frac{z}{5}\)và \(x.y.z=810\)
Đặt \(\frac{x}{2}=\frac{y}{3}=\frac{z}{5}=k\)
\(\Rightarrow x=2k;y=3k;z=5k\)
Vì \(x.y.z=810\)nên \(2k.3k.5k=810\)
\(\Rightarrow30.k^3=810\)
\(\Rightarrow k^3=810:30\)
\(\Rightarrow k^3=27\)
\(\Rightarrow k=3\)
Với \(k=3\)thì \(x=6\); \(y=9\); \(z=15\)
Vậy \(x=6\); \(y=9\); \(z=15\)
Mk chỉ làm đc vậy thui bn à! Xin lỗi thật nhiều nha
a)
\(\begin{array}{l}x.\frac{{14}}{{27}} = \frac{{ - 7}}{9}\\x = \frac{{ - 7}}{9}:\frac{{14}}{{27}}\\x = \frac{{ - 7}}{9}.\frac{{27}}{{14}}\\x = \frac{{ - 3}}{2}\end{array}\)
Vậy \(x = \frac{{ - 3}}{2}\).
b)
\(\begin{array}{l}\left( {\frac{{ - 5}}{9}} \right):x = \frac{2}{3}\\x = \left( {\frac{{ - 5}}{9}} \right):\frac{2}{3}\\x = \left( {\frac{{ - 5}}{9}} \right).\frac{3}{2}\\x = \frac{{ - 5}}{6}\end{array}\)
Vậy \(x = \frac{{ - 5}}{6}\).
c)
\(\begin{array}{l}\frac{2}{5}:x = \frac{1}{{16}}:0,125\\\frac{2}{5}:x = \frac{1}{{16}}:\frac{1}{8}\\\frac{2}{5}:x = \frac{1}{{16}}.8\\\frac{2}{5}:x = \frac{1}{2}\\x = \frac{2}{5}:\frac{1}{2}\\x = \frac{2}{5}.2\\x = \frac{4}{5}\end{array}\)
Vậy \(x = \frac{4}{5}\)
d)
\(\begin{array}{l} - \frac{5}{{12}}x = \frac{2}{3} - \frac{1}{2}\\ - \frac{5}{{12}}x = \frac{4}{6} - \frac{3}{6}\\ - \frac{5}{{12}}x = \frac{1}{6}\\x = \frac{1}{6}:\left( { - \frac{5}{{12}}} \right)\\x = \frac{1}{6}.\frac{{ - 12}}{5}\\x = \frac{{ - 2}}{5}\end{array}\)
Vậy \(x = \frac{{ - 2}}{5}\).
Chú ý: Khi trình bày lời giải bài tìm x, sau khi tính xong, ta phải kết luận.