450-4x-0.1x^2=0

Solution for 450-4x-0.1x^2=0 equation:

450-4x-0.1x^2=0

a = -0.1; b = -4; c = +450;
Δ = b2-4ac
Δ = -42-4·(-0.1)·450
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-14}{2*-0.1}=\frac{-10}{-0.2}
=+50
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+14}{2*-0.1}=\frac{18}{-0.2}
=-90
$