Bài 3:
`a)x(x-1)=0`
`⇔`\(\left[ \begin{array}{l}x=0\\x-1=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=0\\x=1\end{array} \right.\)
Vậy `x=0` hoặc `x=1`
`b)3x²-6x=0`
`⇔3x(x-2)=0`
`⇔`\(\left[ \begin{array}{l}3x=0\\x-2=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=0\\x=2\end{array} \right.\)
Vậy `x=0` hoặc `x=2`
`c)x(x-6)+10(x-6)=0`
`⇔(x-6)(x+10)=0`
`⇔`\(\left[ \begin{array}{l}x-6=0\\x+10=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=6\\x=-10\end{array} \right.\)
Vậy `x=6` hoặc `x=-10`
`d)3x(x-10)=x-10`
`⇔3x(x-10)-(x-10)=0`
`⇔(x-10)(3x-1)=0`
`⇔`\(\left[ \begin{array}{l}x-10=0\\3x-1=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=10\\x=\dfrac{1}{3}\end{array} \right.\)
Vậy `x=10` hoặc `x=1/3`
`e)x(x+5)-2x-10=0`
`⇔x(x+5)-2(x+5)=0`
`⇔(x+5)(x-2)=0`
`⇔`\(\left[ \begin{array}{l}x+5=0\\x-2=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=-5\\x=2\end{array} \right.\)
Vậy `x=-5` hoặc `x=2`
`f)x(x+7)=4x+28`
`⇔x(x+7)=4(x+7)`
`⇔x(x+7)-4(x+7)=0`
`⇔(x+7)(x-4)=0`
`⇔`\(\left[ \begin{array}{l}x+7=0\\x-4=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=-7\\x=4\end{array} \right.\)
Vậy `x=-7` hoặc `x=4`
`g)x³-16x=0`
`⇔x(x²-16)=0`
`⇔x(x²-4²)=0`
`⇔x(x+4)(x-4)=0`
`⇔`\(\left[ \begin{array}{l}x=0\\x+4=0\\x-4=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=0\\x=-4\\x=4\end{array} \right.\)
Vậy `x=0` hoặc `x=-4` hoặc `x=4`
`h)x(x-5)=5-x`
`⇔x(x-5)=-(x-5)`
`⇔x(x-5)+(x-5)=0`
`⇔(x-5)(x+1)=0`
`⇔`\(\left[ \begin{array}{l}x-5=0\\x+1=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=5\\x=-1\end{array} \right.\)
Vậy `x=5` hoặc `x=-1`
`i)(x+2)²=3x+6`
`⇔(x+2)²=3(x+2)`
`⇔(x+2)²-3(x+2)=0`
`⇔(x+2)(x+2-3)=0`
`⇔(x+2)(x-1)=0`
`⇔`\(\left[ \begin{array}{l}x+2=0\\x-1=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=-2\\x=1\end{array} \right.\)
Vậy `x=-2` hoặc `x=1`
