X+.02x^2=100

Solution for X+.02x^2=100 equation:

X+.02X^2=100

We move all terms to the left:

X+.02X^2-(100)=0

a = .02; b = 1; c = -100;
Δ = b2-4ac
Δ = 12-4·.02·(-100)
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-3}{2*.02}=\frac{-4}{0.04}
=-100
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+3}{2*.02}=\frac{2}{0.04}
=50
$