811=(0.04x^2)+(16x)

Solution for 811=(0.04x^2)+(16x) equation:

811=(0.04x^2)+(16x)

We move all terms to the left:

811-((0.04x^2)+(16x))=0


We calculate terms in parentheses: -((0.04x^2)+16x), so:

(0.04x^2)+16x

We add all the numbers together, and all the variables

16x+(0.04x^2)

We get rid of parentheses

0.04x^2+16x

Back to the equation:

-(0.04x^2+16x)


We get rid of parentheses

-0.04x^2-16x+811=0

a = -0.04; b = -16; c = +811;
Δ = b2-4ac
Δ = -162-4·(-0.04)·811
Δ = 385.76
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{-(-16)-\sqrt{385.76}}{2*-0.04}=\frac{16-\sqrt{385.76}}{-0.08}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+\sqrt{385.76}}{2*-0.04}=\frac{16+\sqrt{385.76}}{-0.08}
$