3x(x-3)=3x-9

Solution for 3x(x-3)=3x-9 equation:

3x(x-3)=3x-9

We move all terms to the left:

3x(x-3)-(3x-9)=0

We multiply parentheses

3x^2-9x-(3x-9)=0

We get rid of parentheses

3x^2-9x-3x+9=0

We add all the numbers together, and all the variables

3x^2-12x+9=0

a = 3; b = -12; c = +9;
Δ = b2-4ac
Δ = -122-4·3·9
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-6}{2*3}=\frac{6}{6}
=1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+6}{2*3}=\frac{18}{6}
=3
$