Question

Giải các phương trình :

a) 5 + 3x = 17 – 2x                                                            b) ( 3x – 4)( 2 – 4x)=0

Answer 1

`a)5+3x=17-2x`

`<=>3x+2x=17-5`

`<=>5x=12`

`<=>x=12/5`     Vậy `S={12/5}`

`b)(3x-4)(2-4x)=0`

`<=>` $\left[\begin{matrix} 3x-4=0\\ 2-4x=0\end{matrix}\right.$

`<=>` $\left[\begin{matrix} x=\dfrac{4}{3}\\ x=\dfrac{1}{2}\end{matrix}\right.$

Vậy `S={4/3;1/2}`

Answer 2

a) 5+3x = 17 - 2x

⇔3x + 2x = 17 - 5

⇔    5x    = 12

⇔   x       = 12/5

Vậy S= {12/5}

b) ( 3x - 4) (2 - 4x)= 0

Ta có 3x - 4 =0 hoặc 2 - 4x =0

⇔  3x = 4 hoặc 2 = 4x

⇔  x = 4/3 hoặc x = 4/2

⇔  x = 2

Vậy S = {4/3 ; 2} 

 

Answer 3

a)` 5+3x = 17 - 2x`

`⇔3x + 2x = 17 - 5`

⇔`    5x =12`

` ⇔x = 12/5`

Vậy ` S={12/5}

b)`( 3x - 4) (2 - 4x)= 0`

\(\Leftrightarrow\left[{}\begin{matrix}3x=4\\4x=2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{4}{3}\\x=\dfrac{1}{2}\end{matrix}\right.\)