1-0.02x-0.01x^2=0.65

Solution for 1-0.02x-0.01x^2=0.65 equation:

1-0.02x-0.01x^2=0.65

We move all terms to the left:

1-0.02x-0.01x^2-(0.65)=0

We add all the numbers together, and all the variables

-0.01x^2-0.02x+0.35=0

a = -0.01; b = -0.02; c = +0.35;
Δ = b2-4ac
Δ = -0.022-4·(-0.01)·0.35
Δ = 0.0144
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{-(-0.02)-\sqrt{0.0144}}{2*-0.01}=\frac{0.02-\sqrt{0.0144}}{-0.02}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.02)+\sqrt{0.0144}}{2*-0.01}=\frac{0.02+\sqrt{0.0144}}{-0.02}
$