-2y^2+5y+25=0

Solution for -2y^2+5y+25=0 equation:

-2y^2+5y+25=0

a = -2; b = 5; c = +25;
Δ = b2-4ac
Δ = 52-4·(-2)·25
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-15}{2*-2}=\frac{-20}{-4}
=+5
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+15}{2*-2}=\frac{10}{-4}
=-2+1/2
$