C(x)=0.2X^2-1.3X+3.4025

Solution for C(x)=0.2X^2-1.3X+3.4025 equation:

(C)=0.2C^2-1.3C+3.4025

We move all terms to the left:

(C)-(0.2C^2-1.3C+3.4025)=0

We get rid of parentheses

-0.2C^2+C+1.3C-3.4025=0

We add all the numbers together, and all the variables

-0.2C^2+2.3C-3.4025=0

a = -0.2; b = 2.3; c = -3.4025;
Δ = b2-4ac
Δ = 2.32-4·(-0.2)·(-3.4025)
Δ = 2.568
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$C_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$C_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$C_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2.3)-\sqrt{2.568}}{2*-0.2}=\frac{-2.3-\sqrt{2.568}}{-0.4}
$
$C_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2.3)+\sqrt{2.568}}{2*-0.2}=\frac{-2.3+\sqrt{2.568}}{-0.4}
$