15y^2-38y-21=0

Solution for 15y^2-38y-21=0 equation:

15y^2-38y-21=0

a = 15; b = -38; c = -21;
Δ = b2-4ac
Δ = -382-4·15·(-21)
Δ = 2704
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2704}=52$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-38)-52}{2*15}=\frac{-14}{30}
=-7/15
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-38)+52}{2*15}=\frac{90}{30}
=3
$