-4(3x-7)(4x+1)=0

Solution for -4(3x-7)(4x+1)=0 equation:

-4(3x-7)(4x+1)=0

We multiply parentheses ..

-4(+12x^2+3x-28x-7)=0

We multiply parentheses

-48x^2-12x+112x+28=0

We add all the numbers together, and all the variables

-48x^2+100x+28=0

a = -48; b = 100; c = +28;
Δ = b2-4ac
Δ = 1002-4·(-48)·28
Δ = 15376
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{15376}=124$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(100)-124}{2*-48}=\frac{-224}{-96}
=2+1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(100)+124}{2*-48}=\frac{24}{-96}
=-1/4
$