20x2+80x-1=39

Solution for 20x2+80x-1=39 equation:

20x^2+80x-1=39

We move all terms to the left:

20x^2+80x-1-(39)=0

We add all the numbers together, and all the variables

20x^2+80x-40=0

a = 20; b = 80; c = -40;
Δ = b2-4ac
Δ = 802-4·20·(-40)
Δ = 9600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{9600}=\sqrt{1600*6}=\sqrt{1600}*\sqrt{6}=40\sqrt{6}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(80)-40\sqrt{6}}{2*20}=\frac{-80-40\sqrt{6}}{40}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(80)+40\sqrt{6}}{2*20}=\frac{-80+40\sqrt{6}}{40}
$