15a^2-16a-15=0

Solution for 15a^2-16a-15=0 equation:

15a^2-16a-15=0

a = 15; b = -16; c = -15;
Δ = b2-4ac
Δ = -162-4·15·(-15)
Δ = 1156
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1156}=34$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-34}{2*15}=\frac{-18}{30}
=-3/5
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+34}{2*15}=\frac{50}{30}
=1+2/3
$