8x^2-392x-2640=0

Solution for 8x^2-392x-2640=0 equation:

8x^2-392x-2640=0

a = 8; b = -392; c = -2640;
Δ = b2-4ac
Δ = -3922-4·8·(-2640)
Δ = 238144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{238144}=488$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-392)-488}{2*8}=\frac{-96}{16}
=-6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-392)+488}{2*8}=\frac{880}{16}
=55
$