90x=0,3x^2+15x+800

Solution for 90x=0,3x^2+15x+800 equation:

90x=0.3x^2+15x+800

We move all terms to the left:

90x-(0.3x^2+15x+800)=0

We get rid of parentheses

-0.3x^2+90x-15x-800=0

We add all the numbers together, and all the variables

-0.3x^2+75x-800=0

a = -0.3; b = 75; c = -800;
Δ = b2-4ac
Δ = 752-4·(-0.3)·(-800)
Δ = 4665
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{-(75)-\sqrt{4665}}{2*-0.3}=\frac{-75-\sqrt{4665}}{-0.6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(75)+\sqrt{4665}}{2*-0.3}=\frac{-75+\sqrt{4665}}{-0.6}
$