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\(\dfrac{2x-1}{3}=\dfrac{7}{27\left(2x+1\right)}\)
\(\Leftrightarrow27\left(4x^2-1\right)=21\)
\(\Leftrightarrow4x^2-1=\dfrac{7}{9}\)
\(\Leftrightarrow4x^2=\dfrac{16}{9}\)
\(\Leftrightarrow x^2=\dfrac{4}{9}\)
=>x=2/3 hoặc x=-2/3
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, \(\frac{37-x}{x+13}=\frac{3}{7}\)
\(\Leftrightarrow7\left(37-x\right)=3\left(x+13\right)\)
\(\Leftrightarrow259-7x=3x+39\)
\(\Leftrightarrow-10x=-220\)
\(\Leftrightarrow x=22\)
\(3,8:\left(2x\right)=\frac{1}{4}:2\frac{2}{3}\)
\(3,8:\left(2x\right)=\frac{3}{32}\)
\(\Rightarrow2x=3,8:\frac{3}{32}\)
\(\Rightarrow x=\frac{608}{15}:2=\frac{304}{15}\)
\(\left(a\right)\) tức là bài a hay là gt trog tỉ lệ thức v pn?
a)\(\frac{x-1}{x+2}=\frac{x-2}{x+3}\Rightarrow\left(x-1\right)\left(x+3\right)=\left(x+2\right)\left(x-2\right)\)
\(\Rightarrow x^2+2x-3=x^2-4\)
\(\Rightarrow2x=-1\)
\(\Rightarrow x=-\frac{1}{2}\)
b)\(\frac{37-x}{x+13}=\frac{3}{7}\)\(\Rightarrow7\left(37-x\right)=3\left(x+13\right)\)
\(\Rightarrow259-7x=3x+39\)
\(\Rightarrow10x=220\)
\(\Rightarrow x=22\)
Bài 2:
a: =>x/4=1/8
hay x=1/2
b: \(\Leftrightarrow\dfrac{x}{-5}=\dfrac{11}{6}\)
hay x=-55/6
c: \(\Leftrightarrow\dfrac{-3.5}{x}=\dfrac{4.25}{8}\)
hay x=-112/17
\(2x+\frac{1}{-3}=\frac{-7}{11}\)
\(2x=\frac{-7}{11}-\frac{1}{-3}\)
\(2x=\frac{-10}{33}\)
\(x=\frac{-10}{33}\) : \(2\)
\(x=\frac{-5}{33}\)
Vậy \(x=\frac{-5}{33}\)