90x-0.15x^2=0

Solution for 90x-0.15x^2=0 equation:

90x-0.15x^2=0

a = -0.15; b = 90; c = 0;
Δ = b2-4ac
Δ = 902-4·(-0.15)·0
Δ = 8100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8100}=90$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(90)-90}{2*-0.15}=\frac{-180}{-0.3}
=+600
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(90)+90}{2*-0.15}=\frac{0}{-0.3}
=0
$