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

Solution for 3(2x-1)(4x+5)=0 equation:

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

We multiply parentheses ..

3(+8x^2+10x-4x-5)=0

We multiply parentheses

24x^2+30x-12x-15=0

We add all the numbers together, and all the variables

24x^2+18x-15=0

a = 24; b = 18; c = -15;
Δ = b2-4ac
Δ = 182-4·24·(-15)
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-42}{2*24}=\frac{-60}{48}
=-1+1/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+42}{2*24}=\frac{24}{48}
=1/2
$