4(x+5)(3X-1)=0

Solution for 4(x+5)(3X-1)=0 equation:

4(x+5)(3x-1)=0

We multiply parentheses ..

4(+3x^2-1x+15x-5)=0

We multiply parentheses

12x^2-4x+60x-20=0

We add all the numbers together, and all the variables

12x^2+56x-20=0

a = 12; b = 56; c = -20;
Δ = b2-4ac
Δ = 562-4·12·(-20)
Δ = 4096
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4096}=64$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(56)-64}{2*12}=\frac{-120}{24}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(56)+64}{2*12}=\frac{8}{24}
=1/3
$