bài 1
a)
`4x(x-2y)+8y(2y-x)`
`=4x(x-2y)-8y(x-2y)`
`=(4x-8y)(x-2y)`
b)
`(x+5)^2-3(x+5)`
`=(x+5-3)(x+5)`
`=(x+2)(x+5)`
c)
`2x(x-3)+(x-3)^2`
`=(2x-x+3)(x-3)`
`=(x+3)(x-3)`
d)
`x(x-7)+(7-x)^2`
`=x(x-7)+(x-7)^2`
`=(x+x-7)(x-7)`
`=(2x-7)(x-7)`
e)
`3x(x-9)^2-(9-x)^3`
`=3x(9-x)^2-(9-x)^3`
`=(3x-9+x)(9-x)^2`
`=(4x-9)(9-x)^2`
bài 2
a)
`x(2x-1)+1/3-2/3x=0`
`<=>x(2x-1)+1/3(1-2x)=0`
`<=>x(2x-1)-1/3(2x-1)=0`
`<=>(x-1/3)(2x-1)=0`
`<=>` \(\left[ \begin{array}{l}x-\frac{1}{3}=0\\2x-1=0\end{array}\right.\)
`<=>` \(\left[ \begin{array}{l}x=\frac{1}{3}\\2x=1\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=\frac{1}{3}\\x=\frac{1}{2}\end{array} \right.\)
vậy `S={1/3;1/2}`
b)
`3x(x-2)+2(2-x)=0`
`<=>3x(x-2)-2(x-2)=0`
`<=>(3x-2)(x-2)=0`
`<=>` \(\left[ \begin{array}{l}3x-2=0\\x-2=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}3x=2\\x=2\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=\frac{2}{3}\\x=2\end{array} \right.\)
vậy `S={2/3;2}`
c)
`x(x-4)+(x-4)^2=0`
`<=>(x+x-4)(x-4)=0`
`<=>(2x-4)(x-4)=0`
`<=>` \(\left[ \begin{array}{l}2x-4=0\\x-4=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}2x=4\\x=4\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=2\\x=4\end{array} \right.\)
vậy `S={4;2}`
