-0.004x^2+8x=2080

Solution for -0.004x^2+8x=2080 equation:

-0.004x^2+8x=2080

We move all terms to the left:

-0.004x^2+8x-(2080)=0

a = -0.004; b = 8; c = -2080;
Δ = b2-4ac
Δ = 82-4·(-0.004)·(-2080)
Δ = 30.72
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{-(8)-\sqrt{30.72}}{2*-0.004}=\frac{-8-\sqrt{30.72}}{-0.008}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+\sqrt{30.72}}{2*-0.004}=\frac{-8+\sqrt{30.72}}{-0.008}
$