`a)4x²=4x-1`
`⇔4x²-4x+1=0`
`⇔(2x)^2-2.2x.1+1²=0`
`⇔(2x-1)²=0`
`⇔2x-1=0`
`⇔2x=1`
`⇔x=1/2`
Vậy `x=1/2`
`b)4x²-4=0`
`⇔4(x²-1)=0`
`⇔x²-1=0`
`⇔(x+1)(x-1)=0`
`⇔`\(\left[ \begin{array}{l}x+1=0\\x-1=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=-1\\x=1\end{array} \right.\)
Vậy `x=-1` hoặc `x=1`
`c)18x²-2=0`
`⇔2(9x²-1)=0`
`⇔9x²-1=0`
`⇔(3x+1)(3x-1)=0`
`⇔`\(\left[ \begin{array}{l}3x+1=0\\3x-1=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}3x=-1\\3x=1\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=-\dfrac{1}{3}\\x=\dfrac{1}{3}\end{array} \right.\)
Vậy `x=-1/3` hoặc `x=1/3`
`d)8x³+6x-1=12x²`
`⇔8x³+6x-1-12x²=0`
`⇔8x³-12x²+6x-1=0`
`⇔(2x)³-3.(2x)².1+3.2x.1²-1³=0`
`⇔(2x-1)³=0`
`⇔2x-1=0`
`⇔2x=1`
`⇔x=1/2`
Vậy `x=1/2`
`e)(2x+1)²-(x-3)²=0`
`⇔(2x+1+x-3)(2x+1-x+3)=0`
`⇔(3x-2)(x+4)=0`
`⇔`\(\left[ \begin{array}{l}3x-2=0\\x+4=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=\dfrac{2}{3}\\x=-4\end{array} \right.\)
Vậy `x=2/3` hoặc `x=-4`
