-5x2-80x+320=3

Solution for -5x2-80x+320=3 equation:

-5x^2-80x+320=3

We move all terms to the left:

-5x^2-80x+320-(3)=0

We add all the numbers together, and all the variables

-5x^2-80x+317=0

a = -5; b = -80; c = +317;
Δ = b2-4ac
Δ = -802-4·(-5)·317
Δ = 12740
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:

$\sqrt{\Delta}=\sqrt{12740}=\sqrt{196*65}=\sqrt{196}*\sqrt{65}=14\sqrt{65}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-80)-14\sqrt{65}}{2*-5}=\frac{80-14\sqrt{65}}{-10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-80)+14\sqrt{65}}{2*-5}=\frac{80+14\sqrt{65}}{-10}
$