25k^2-10k-8=0

Solution for 25k^2-10k-8=0 equation:

25k^2-10k-8=0

a = 25; b = -10; c = -8;
Δ = b2-4ac
Δ = -102-4·25·(-8)
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-30}{2*25}=\frac{-20}{50}
=-2/5
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+30}{2*25}=\frac{40}{50}
=4/5
$