2y^2+2y=84

Solution for 2y^2+2y=84 equation:

2y^2+2y=84

We move all terms to the left:

2y^2+2y-(84)=0

a = 2; b = 2; c = -84;
Δ = b2-4ac
Δ = 22-4·2·(-84)
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-26}{2*2}=\frac{-28}{4}
=-7
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+26}{2*2}=\frac{24}{4}
=6
$