2y^2+8y=-5

Solution for 2y^2+8y=-5 equation:

2y^2+8y=-5

We move all terms to the left:

2y^2+8y-(-5)=0

We add all the numbers together, and all the variables

2y^2+8y+5=0

a = 2; b = 8; c = +5;
Δ = b2-4ac
Δ = 82-4·2·5
Δ = 24
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:

$\sqrt{\Delta}=\sqrt{24}=\sqrt{4*6}=\sqrt{4}*\sqrt{6}=2\sqrt{6}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-2\sqrt{6}}{2*2}=\frac{-8-2\sqrt{6}}{4}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+2\sqrt{6}}{2*2}=\frac{-8+2\sqrt{6}}{4}
$