-2x^2-10x+168=0

Solution for -2x^2-10x+168=0 equation:

-2x^2-10x+168=0

a = -2; b = -10; c = +168;
Δ = b2-4ac
Δ = -102-4·(-2)·168
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-38}{2*-2}=\frac{-28}{-4}
=+7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+38}{2*-2}=\frac{48}{-4}
=-12
$