-2y^2=25+15y

Solution for -2y^2=25+15y equation:

-2y^2=25+15y

We move all terms to the left:

-2y^2-(25+15y)=0

We add all the numbers together, and all the variables

-2y^2-(15y+25)=0

We get rid of parentheses

-2y^2-15y-25=0

a = -2; b = -15; c = -25;
Δ = b2-4ac
Δ = -152-4·(-2)·(-25)
Δ = 25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25}=5$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-5}{2*-2}=\frac{10}{-4}
=-2+1/2
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+5}{2*-2}=\frac{20}{-4}
=-5
$