-2y^2+6y+8=0

Solution for -2y^2+6y+8=0 equation:

-2y^2+6y+8=0

a = -2; b = 6; c = +8;
Δ = b2-4ac
Δ = 62-4·(-2)·8
Δ = 100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{100}=10$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-10}{2*-2}=\frac{-16}{-4}
=+4
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+10}{2*-2}=\frac{4}{-4}
=-1
$