(3x+9)(1-2x)=0

Solution for (3x+9)(1-2x)=0 equation:

(3x+9)(1-2x)=0

We add all the numbers together, and all the variables

(3x+9)(-2x+1)=0

We multiply parentheses ..

(-6x^2+3x-18x+9)=0

We get rid of parentheses

-6x^2+3x-18x+9=0

We add all the numbers together, and all the variables

-6x^2-15x+9=0

a = -6; b = -15; c = +9;
Δ = b2-4ac
Δ = -152-4·(-6)·9
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-21}{2*-6}=\frac{-6}{-12}
=1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+21}{2*-6}=\frac{36}{-12}
=-3
$