20x^2-66x=-40

Solution for 20x^2-66x=-40 equation:

20x^2-66x=-40

We move all terms to the left:

20x^2-66x-(-40)=0

We add all the numbers together, and all the variables

20x^2-66x+40=0

a = 20; b = -66; c = +40;
Δ = b2-4ac
Δ = -662-4·20·40
Δ = 1156
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1156}=34$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-66)-34}{2*20}=\frac{32}{40}
=4/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-66)+34}{2*20}=\frac{100}{40}
=2+1/2
$