5y^2-30y-18=0

Solution for 5y^2-30y-18=0 equation:

5y^2-30y-18=0

a = 5; b = -30; c = -18;
Δ = b2-4ac
Δ = -302-4·5·(-18)
Δ = 1260
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1260}=\sqrt{36*35}=\sqrt{36}*\sqrt{35}=6\sqrt{35}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-6\sqrt{35}}{2*5}=\frac{30-6\sqrt{35}}{10}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+6\sqrt{35}}{2*5}=\frac{30+6\sqrt{35}}{10}
$