-3(2x-16)(x+7)=0

Solution for -3(2x-16)(x+7)=0 equation:

-3(2x-16)(x+7)=0

We multiply parentheses ..

-3(+2x^2+14x-16x-112)=0

We multiply parentheses

-6x^2-42x+48x+336=0

We add all the numbers together, and all the variables

-6x^2+6x+336=0

a = -6; b = 6; c = +336;
Δ = b2-4ac
Δ = 62-4·(-6)·336
Δ = 8100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8100}=90$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-90}{2*-6}=\frac{-96}{-12}
=+8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+90}{2*-6}=\frac{84}{-12}
=-7
$