X+2x2=85

Solution for X+2x2=85 equation:

X+2X^2=85

We move all terms to the left:

X+2X^2-(85)=0

a = 2; b = 1; c = -85;
Δ = b2-4ac
Δ = 12-4·2·(-85)
Δ = 681
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-\sqrt{681}}{2*2}=\frac{-1-\sqrt{681}}{4}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{681}}{2*2}=\frac{-1+\sqrt{681}}{4}
$