Question

Giải các phương trình sau:

3x+7=0; 

2x(x-2)+2x(5-3x)=0;

 

Answer 1

`3x+7=0`

`<=>3x=-7`

`<=>x=-7/3`

Vậy `S={-7/3}`

______________________

`2x(x-2)+2x(5-3x)=0`

`<=>2x(x-2+5-3x)=0`

`<=>2x(3-2x)=0`

`@TH1:2x=0<=>x=0`

`@TH2: 3-2x=0<=>2x=3<=>x=3/2`

Vậy `S={0;3/2}`

Answer 2

3x+7=0

\(\Leftrightarrow3x=-7\Leftrightarrow x=-\dfrac{7}{3}\)

2x(x-2)+2x(5-3x)=0

\(\Leftrightarrow2x\left(x-2+5-3x\right)=0\)

\(\Leftrightarrow2x\left(-2x+3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}2x=0\\-2x=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{-3}{-2}=\dfrac{3}{2}\end{matrix}\right.\)

Answer 3

3x + 7 = 0

\(\Leftrightarrow\) 3x = -7

\(\Leftrightarrow\) x = -7/3

 

2x(x - 2) + 2x(5 - 3x) = 0

\(\Leftrightarrow\) 2x(x - 2 + 5 - 3x) = 0

\(\Leftrightarrow\) 2x(-2x + 3) = 0

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

Answer 4

\(\Leftrightarrow3x=-7\Leftrightarrow x=-\dfrac{7}{3}\)

 

\(\Leftrightarrow2x\left(x-2+5-3x\right)=0\)

\(\Leftrightarrow2x\left(3-2x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}2x=0\\3-2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\-2x=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{3}{2}\end{matrix}\right.\)

Answer 5

3x+7=0

<=> 3x = -7

<=> x = -7/3

Vậy nghiệm của phương trình đã cho là x=-7/3

2x(x - 2) + 2x(5 - 3x) = 0

⇔ 2x(x - 2 + 5 - 3x) = 0

⇔ 2x(-2x + 3) = 0

<=> \(\left[{}\begin{matrix}2x=0\\-2x+3=0\end{matrix}\right.\)

<=>\(\left[{}\begin{matrix}x=0\\x=\dfrac{3}{2}\end{matrix}\right.\)

Vậy tập nghiệm của phương trình là \(\left\{0,\dfrac{3}{2}\right\}\)