7y^2+18y=-8

Solution for 7y^2+18y=-8 equation:

7y^2+18y=-8

We move all terms to the left:

7y^2+18y-(-8)=0

We add all the numbers together, and all the variables

7y^2+18y+8=0

a = 7; b = 18; c = +8;
Δ = b2-4ac
Δ = 182-4·7·8
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{-(18)-10}{2*7}=\frac{-28}{14}
=-2
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+10}{2*7}=\frac{-8}{14}
=-4/7
$