15q^2-13q-20=0

Solution for 15q^2-13q-20=0 equation:

15q^2-13q-20=0

a = 15; b = -13; c = -20;
Δ = b2-4ac
Δ = -132-4·15·(-20)
Δ = 1369
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$q_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$q_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1369}=37$
$q_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-37}{2*15}=\frac{-24}{30}
=-4/5
$
$q_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+37}{2*15}=\frac{50}{30}
=1+2/3
$