0.85x^2+x+0.15=1

Solution for 0.85x^2+x+0.15=1 equation:

0.85x^2+x+0.15=1

We move all terms to the left:

0.85x^2+x+0.15-(1)=0

We add all the numbers together, and all the variables

0.85x^2+x-0.85=0

a = 0.85; b = 1; c = -0.85;
Δ = b2-4ac
Δ = 12-4·0.85·(-0.85)
Δ = 3.89
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{3.89}}{2*0.85}=\frac{-1-\sqrt{3.89}}{1.7}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{3.89}}{2*0.85}=\frac{-1+\sqrt{3.89}}{1.7}
$