8x^2-30x-128=0

Solution for 8x^2-30x-128=0 equation:

8x^2-30x-128=0

a = 8; b = -30; c = -128;
Δ = b2-4ac
Δ = -302-4·8·(-128)
Δ = 4996
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:

$\sqrt{\Delta}=\sqrt{4996}=\sqrt{4*1249}=\sqrt{4}*\sqrt{1249}=2\sqrt{1249}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-2\sqrt{1249}}{2*8}=\frac{30-2\sqrt{1249}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+2\sqrt{1249}}{2*8}=\frac{30+2\sqrt{1249}}{16}
$