Đáp án + Giải thích các bước giải:
`2)`
`3x²-6x=0`
`3x(x-2)=0`
`⇒ ` $\left[\begin{matrix} 3x=0\\ x-2=0\end{matrix}\right.$ `⇒` $\left[\begin{matrix} x=0\\ x=2\end{matrix}\right.$
Vậy `x=0` hoặc `x=2`
`3)`
`5x(x-200)-x+200=0`
`5x²-1000x-x+200=0`
`5x( x-200)-(x-200)=0`
`(5x-1)(x-200)=0`
`⇒` $\left[\begin{matrix} 5x-1=0\\ x-200=0\end{matrix}\right.$ `⇒` $\left[\begin{matrix} x=\dfrac{1}{5}\\ x=200\end{matrix}\right.$
Vậy `x=1/5` hoặc `x=200`
`4)`
`x³-13x=0`
`x(x-13)=0`
`⇒` $\left[\begin{matrix} x=0\\ x-13=0\end{matrix}\right.$ `⇒` $\left[\begin{matrix} x=0\\ x=13\end{matrix}\right.$
Vậy `x=0` hoăc `x=13`
`5)`
`x(x-6)+10(x-6)=0`
`(x+10)(x-6)=0`
`⇒` $\left[\begin{matrix} x+10=0\\ x-6=0\end{matrix}\right.$ `⇒` $\left[\begin{matrix} x=-10\\ x=6\end{matrix}\right.$
Vậy `x=-10` hoặc `x=6`
`6)`
`(x+2)²=x+2`
`(x+2)(x+2)-(x+2)=0`
`(x+2)(x+2-1)=0`
`(x+2)(x+1)=0`
`⇒` $\left[\begin{matrix} x+2=0\\ x+1=3\end{matrix}\right.$ `⇒` $\left[\begin{matrix} x=-2\\ x=-1\end{matrix}\right.$
Vậy `x=-2` hoặc `x=-1`
`7)`
`x³+4x=0`
`x(x²+4)=0`
`⇒ ` $\left[\begin{matrix} x=0\\ x²+4=0\end{matrix}\right.$ `⇒` $\left[\begin{matrix} x=0\\ x²=-4( vô lí)\end{matrix}\right.$
Vậy `x=0`
