5y^2-13y-28=0

Solution for 5y^2-13y-28=0 equation:

5y^2-13y-28=0

a = 5; b = -13; c = -28;
Δ = b2-4ac
Δ = -132-4·5·(-28)
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-27}{2*5}=\frac{-14}{10}
=-1+2/5
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+27}{2*5}=\frac{40}{10}
=4
$