Question

Bài 1:  Giải các phương trình sau:
a) 7 – 2x = 0          b) (1 – 2x).(3x + 9) = 0
 

Answer 1

`a) 7 - 2x = 0`

`<=> 2x = 7`

`<=> x = 7 / 2`      Vậy `S = { 7 / 2 }`

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`b) ( 1 - 2x ) ( 3x + 9 ) = 0`

`<=>` $\left[\begin{matrix} 1 - 2x=0\\ 3x + 9 =0\end{matrix}\right.$

`<=>` $\left[\begin{matrix} x=\dfrac{1}{2}\\ x =-3\end{matrix}\right.$

Vậy `S = { 1 / 2 ; 3 }`

Answer 2

\(a,\Leftrightarrow-2x=-7\)

\(\Leftrightarrow x=\dfrac{7}{2}\)

\(b,\Leftrightarrow\left[{}\begin{matrix}1-2x=0\\3x+9=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}-2x=-1\\3x=-9\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-3\end{matrix}\right.\)