45=0.4x^2+2x+2

Solution for 45=0.4x^2+2x+2 equation:

45=0.4x^2+2x+2

We move all terms to the left:

45-(0.4x^2+2x+2)=0

We get rid of parentheses

-0.4x^2-2x-2+45=0

We add all the numbers together, and all the variables

-0.4x^2-2x+43=0

a = -0.4; b = -2; c = +43;
Δ = b2-4ac
Δ = -22-4·(-0.4)·43
Δ = 72.8
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{-(-2)-\sqrt{72.8}}{2*-0.4}=\frac{2-\sqrt{72.8}}{-0.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+\sqrt{72.8}}{2*-0.4}=\frac{2+\sqrt{72.8}}{-0.8}
$