`#Sad`
`5)`
`(2-4x)(5-4x)-(4x-1)^2+12x+10 = 0`
`⇔ 10-8x-20x+16x^2-16x^2+8x-1+12x+10 = 0`
`⇔ (16x^2-16x^2)+(-8x-20x+8x+12x)+(10-1+10) = 0`
`⇔ -8x+19 = 0`
`⇔ -8x = -19`
`⇔ x = (19)/8`
`\text{Vậy}` `x=(19)/8`
`6)`
`x^2 = 1`
`⇔` \(\left[ \begin{array}{l}x=1\\x=-1\end{array} \right.\)
`\text{Vậy}` `x=1` `\text{hoặc}` `x=-1`
`7)`
`4x^2-4x+1 = 0`
`⇔ (2x)^2-2. 2x. 1+1 = 0`
`⇔ (2x-1)^2 = 0`
`⇔ 2x-1 = 0`
`⇔ 2x = 1`
`⇔ x = 1/2`
`\text{Vậy}` `x=1/2`
`8)`
`25x^2-10x+1 = 0`
`⇔ (5x)^2-2. 5x. 1+1 = 0`
`⇔ (5x-1)^2 = 0`
`⇔ 5x-1=0`
`⇔ 5x = 1`
`⇔ x = 1/5`
`\text{Vậy}` `x=1/5`
`9)`
`9x^2+24x+15 = 0`
`⇔ 3(3x^2+8x+5) = 0`
`⇔ 3(3x^2+5x+3x+5) = 0`
`⇔ 3[(3x^2+5x)+(3x+5)] = 0`
`⇔ 3[x(3x+5)+(3x+5)] = 0`
`⇔ 3(x+1)(3x+5) = 0`
`⇔ (x+1)(3x+5) = 0`
`⇔` \(\left[ \begin{array}{l}x+1=0\\3x+5=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=-1\\3x=-5\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=-1\\x=-\dfrac{5}{3}\end{array} \right.\)
`\text{Vậy}` `=-1` `\text{hoặc}` `x=-(5)/(3)`
`10)`
`25x^2-15x+2 = 0`
`⇔ 25x^2-10x-5x+2 = 0`
`⇔ (25x^2-5x)-(10x-2) = 0`
`⇔ 5x(5x-1)-2(5x-1) = 0`
`⇔ (5x-2)(5x-1) = 0`
`⇔` \(\left[ \begin{array}{l}5x-2=0\\5x-1=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}5x=2\\5x=1\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=\dfrac{2}{5}\\x=\dfrac{1}{5}\end{array} \right.\)
`\text{Vậy}` `x=2/5` `\text{hoặc}` `x=1/5`
