8x^2-16x-11=0

Solution for 8x^2-16x-11=0 equation:

8x^2-16x-11=0

a = 8; b = -16; c = -11;
Δ = b2-4ac
Δ = -162-4·8·(-11)
Δ = 608
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:

$\sqrt{\Delta}=\sqrt{608}=\sqrt{16*38}=\sqrt{16}*\sqrt{38}=4\sqrt{38}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-4\sqrt{38}}{2*8}=\frac{16-4\sqrt{38}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+4\sqrt{38}}{2*8}=\frac{16+4\sqrt{38}}{16}
$