-56=-0.04x^2+1.3x+56

Solution for -56=-0.04x^2+1.3x+56 equation:

-56=-0.04x^2+1.3x+56

We move all terms to the left:

-56-(-0.04x^2+1.3x+56)=0

We get rid of parentheses

0.04x^2-1.3x-56-56=0

We add all the numbers together, and all the variables

0.04x^2-1.3x-112=0

a = 0.04; b = -1.3; c = -112;
Δ = b2-4ac
Δ = -1.32-4·0.04·(-112)
Δ = 19.61
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{-(-1.3)-\sqrt{19.61}}{2*0.04}=\frac{1.3-\sqrt{19.61}}{0.08}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.3)+\sqrt{19.61}}{2*0.04}=\frac{1.3+\sqrt{19.61}}{0.08}
$