8x^2-30x-20=0

Solution for 8x^2-30x-20=0 equation:

8x^2-30x-20=0

a = 8; b = -30; c = -20;
Δ = b2-4ac
Δ = -302-4·8·(-20)
Δ = 1540
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:

$\sqrt{\Delta}=\sqrt{1540}=\sqrt{4*385}=\sqrt{4}*\sqrt{385}=2\sqrt{385}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-2\sqrt{385}}{2*8}=\frac{30-2\sqrt{385}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+2\sqrt{385}}{2*8}=\frac{30+2\sqrt{385}}{16}
$