15b^2-6b-9=0

Solution for 15b^2-6b-9=0 equation:

15b^2-6b-9=0

a = 15; b = -6; c = -9;
Δ = b2-4ac
Δ = -62-4·15·(-9)
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-24}{2*15}=\frac{-18}{30}
=-3/5
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+24}{2*15}=\frac{30}{30}
=1
$