18-0,1x^2=0,5x+3

Solution for 18-0,1x^2=0,5x+3 equation:

18-0.1x^2=0.5x+3

We move all terms to the left:

18-0.1x^2-(0.5x+3)=0

We get rid of parentheses

-0.1x^2-0.5x-3+18=0

We add all the numbers together, and all the variables

-0.1x^2-0.5x+15=0

a = -0.1; b = -0.5; c = +15;
Δ = b2-4ac
Δ = -0.52-4·(-0.1)·15
Δ = 6.25
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{-(-0.5)-\sqrt{6.25}}{2*-0.1}=\frac{0.5-\sqrt{6.25}}{-0.2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.5)+\sqrt{6.25}}{2*-0.1}=\frac{0.5+\sqrt{6.25}}{-0.2}
$