g) \(|9-7x|=5x-3\)
Vì \(|9-7x|\ge0;\forall x\)
\(\Rightarrow5x-3\ge0\)
\(\Rightarrow x\ge\frac{3}{5}\)
Ta có: \(|9-7x|=5x-3\)
\(\Leftrightarrow\orbr{\begin{cases}9-7x=5x-3\\9-7x=3-5x\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}-7x-5x=-3-9\\-7x+5x=3-9\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}-12x=-12\\-2x=-6\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=1>\frac{3}{5}\left(chon\right)\\x=3>\frac{3}{5}\left(chon\right)\end{cases}}\)
Vậy \(x\in\left\{1;3\right\}\)
h) \(8x-|4x+1|=x+2\)
\(\Leftrightarrow|4x+1|=7x+2\)
Vì \(|4x+1|\ge0;\forall x\)
\(\Rightarrow7x+2\ge0\)
\(\Rightarrow x\ge\frac{-2}{7}\)
Ta có: \(|4x+1|=7x+2\)
\(\Leftrightarrow\orbr{\begin{cases}4x+1=7x+2\\4x+1=-7x-2\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}-3x=1\\11x=-3\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=\frac{-1}{3}< \frac{-2}{7}\left(loai\right)\\x=\frac{-3}{11}>\frac{-2}{7}\left(chon\right)\end{cases}}\)
Vậy \(x=\frac{-3}{11}\)
[ 212 + ( 48 - 2 . x . x2 ) : 40 - 3 = 3
[ 212 + ( 48 - 2 . x . x2 ) : 40 = 3 + 3 = 6
[ 212 + ( 48 - 2 . x . x2 ) = 6 . 40 = 240
=> 48 - 2 . x . x2 = 240 - 212 = 28
2 . x . x2 = 48 - 28 = 20
x. x2 = 20 : 2 = 10