3x(x-10)-168=0

Solution for 3x(x-10)-168=0 equation:

3x(x-10)-168=0

We multiply parentheses

3x^2-30x-168=0

a = 3; b = -30; c = -168;
Δ = b2-4ac
Δ = -302-4·3·(-168)
Δ = 2916
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2916}=54$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-54}{2*3}=\frac{-24}{6}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+54}{2*3}=\frac{84}{6}
=14
$