Y=-5x^2-30x-15

Solution for Y=-5x^2-30x-15 equation:

=-5Y^2-30Y-15

We move all terms to the left:

-(-5Y^2-30Y-15)=0

We get rid of parentheses

5Y^2+30Y+15=0

a = 5; b = 30; c = +15;
Δ = b2-4ac
Δ = 302-4·5·15
Δ = 600
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:

$\sqrt{\Delta}=\sqrt{600}=\sqrt{100*6}=\sqrt{100}*\sqrt{6}=10\sqrt{6}$
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-10\sqrt{6}}{2*5}=\frac{-30-10\sqrt{6}}{10}
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+10\sqrt{6}}{2*5}=\frac{-30+10\sqrt{6}}{10}
$