$\text{5. 3x.(x - 2008)- x +2008=0}$
`<=>3x(x - 2008) - (x - 2008)=0`
`<=>(3x - 1)(x - 2008)=0
`<=>3x - 1=0`
`x - 2008=0`
`<=>3x=1`
`x=2008`
$\text{<=>x=}$ `1/3`
`x=2008`
`1. x^2 + 6x + 5=0`
`<=>x^2 + 5x + x + 5=0`
`<=>x(x + 5) +(x + 5)=0`
`<=>(x + 1)(x + 5)=0`
`<=>x + 1=0`
`x+5=0`
`<=>x=-1`
`x=-5`
`2. x^3 - 9x=0`
`<=>x(x^2 - 9)=0`
`<=>x(x - 3)(x + 3)=0`
`<=>x=0`
`x - 3=0`
`x + 3=0`
`<=>x=0`
`x=3`
`x=-3`
`3. x^2 + 25=10x`
`<=>x^2 + 25 - 10x=0`
`<=>(x - 5)^2=0`
`<=>x - 5=0`
`<=>x=5`
`4. (2x - 3)(3 - 4x)=0`
`<=>2x - 3=0`
`3 - 4x=0`
`<=>2x=3`
`-4x=-3`
`<=>x=3/2`
`x=3/4`
`6.x^2 - 6x + 9=0`
`<=>(x - 3 )^2=0`
`<=>x - 3=0`
`<=>x=3`