7,8x+( -2,7 . x ) = 10 , 2
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\(8x=7,8x+25\)
\(8x-7,8x=25\)
\(0,2x=25\)
\(x=25:0,2\)
\(x=125\left(tm\right)\)
Vậy ....
\(8x=7,8x+25\Leftrightarrow8x-7,8x=25\Leftrightarrow0,2x=25\Leftrightarrow x=\dfrac{25}{0,2}=125\)
vậy \(x=125\)
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\(a.x=\frac{3}{4}-\frac{1}{2}=\frac{1}{4}\)
\(b.x=\frac{4}{7}:\frac{4}{5}=\frac{5}{7}\)
\(c.8x-7,8x=25\)
\(0,2x=25\Rightarrow x=125\)
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\(6x-7,8x=-36\)
\(\left(6-7,8\right)x=-36\)
\(\frac{-9}{5}x=-36\)
\(x=\left(-36\right):\frac{-9}{5}\)
\(x=20\)
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Bài làm :
\(1\text{)}8x=7,8x+25\Leftrightarrow8x-7,8x=25\Leftrightarrow0,2x=25\Leftrightarrow x=25\div0,2=125\)
\(2\text{)}\left|x+7\right|-3=2\Leftrightarrow\left|x+7\right|=5\Leftrightarrow\orbr{\begin{cases}x+7=5\\x+7=-5\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=-12\end{cases}}\)
\(3\text{)}\left(2x-5\right)\div3=7\Leftrightarrow2x-5=21\Leftrightarrow2x=26\Leftrightarrow x=13\)
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Trừ cả hai vế đi 7,8x
25 = 0,2x
x = 25 : 0,2
x = 125