`1)(x+1)²-4x=0`
`⇔x²+2x+1-4x=0`
`⇔x²-2x+1=0`
`⇔(x-1)²=0`
`⇔x-1=0`
`⇔x=1`
Vậy `x=1`
`2)(2x+3)²-12(x+3/2)=0`
`⇔4x²+12x+9-12x-18=0`
`⇔4x²-9=0`
`⇔(2x+3)(2x-3)=0`
`⇔`\(\left[ \begin{array}{l}2x+3=0\\2x-3=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}2x=-3\\2x=3\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=-\dfrac{3}{2}\\x=\dfrac{3}{2}\end{array} \right.\)
Vậy `x=-3/2` hoặc `x=3/2`
`3)x²+6x+9=0`
`⇔x²+2.x.3+3²=0`
`⇔(x+3)²=0`
`⇔x+3=0`
`⇔x=-3`
Vậy `x=-3`
`4)25x²-20x+4=0`
`⇔(5x)²-2.5x.2+2²=0`
`⇔(5x-2)²=0`
`⇔5x-2=0`
`⇔5x=2`
`⇔x=2/5`
Vậy `x=2/5`
`5)25x²-9=0`
`⇔(5x)²-3²=0`
`⇔(5x+3)(5x-3)=0`
`⇔`\(\left[ \begin{array}{l}5x+3=0\\5x-3=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}5x=-3\\5x=3\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=-\dfrac{3}{5}\\x=\dfrac{3}{5}\end{array} \right.\)
Vậy `x=-3/5` hoặc `x=3/5`
`6)x²-16=0`
`⇔x²=16`
`⇔x²=4²`
`⇔x=±4`
Vậy `x=±4`