8r^2-24r-8=0

Solution for 8r^2-24r-8=0 equation:

8r^2-24r-8=0

a = 8; b = -24; c = -8;
Δ = b2-4ac
Δ = -242-4·8·(-8)
Δ = 832
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{832}=\sqrt{64*13}=\sqrt{64}*\sqrt{13}=8\sqrt{13}$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-8\sqrt{13}}{2*8}=\frac{24-8\sqrt{13}}{16}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+8\sqrt{13}}{2*8}=\frac{24+8\sqrt{13}}{16}
$