(9x-3)(4+x)=0

Solution for (9x-3)(4+x)=0 equation:

(9x-3)(4+x)=0

We add all the numbers together, and all the variables

(9x-3)(x+4)=0

We multiply parentheses ..

(+9x^2+36x-3x-12)=0

We get rid of parentheses

9x^2+36x-3x-12=0

We add all the numbers together, and all the variables

9x^2+33x-12=0

a = 9; b = 33; c = -12;
Δ = b2-4ac
Δ = 332-4·9·(-12)
Δ = 1521
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1521}=39$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(33)-39}{2*9}=\frac{-72}{18}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(33)+39}{2*9}=\frac{6}{18}
=1/3
$