(x)=0.2x^2-40x+6,658

Solution for (x)=0.2x^2-40x+6,658 equation:

(x)=0.2x^2-40x+6.658

We move all terms to the left:

(x)-(0.2x^2-40x+6.658)=0

We get rid of parentheses

-0.2x^2+x+40x-6.658=0

We add all the numbers together, and all the variables

-0.2x^2+41x-6.658=0

a = -0.2; b = 41; c = -6.658;
Δ = b2-4ac
Δ = 412-4·(-0.2)·(-6.658)
Δ = 1675.6736
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{-(41)-\sqrt{1675.6736}}{2*-0.2}=\frac{-41-\sqrt{1675.6736}}{-0.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(41)+\sqrt{1675.6736}}{2*-0.2}=\frac{-41+\sqrt{1675.6736}}{-0.4}
$