(2x+16)(3x-21)=0

Solution for (2x+16)(3x-21)=0 equation:

(2x+16)(3x-21)=0

We multiply parentheses ..

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

We get rid of 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
$