8x2-10x-20=0

Solution for 8x2-10x-20=0 equation:

8x^2-10x-20=0

a = 8; b = -10; c = -20;
Δ = b2-4ac
Δ = -102-4·8·(-20)
Δ = 740
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{740}=\sqrt{4*185}=\sqrt{4}*\sqrt{185}=2\sqrt{185}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-2\sqrt{185}}{2*8}=\frac{10-2\sqrt{185}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+2\sqrt{185}}{2*8}=\frac{10+2\sqrt{185}}{16}
$