400q^2-1600=0

Solution for 400q^2-1600=0 equation:

400q^2-1600=0

a = 400; b = 0; c = -1600;
Δ = b2-4ac
Δ = 02-4·400·(-1600)
Δ = 2560000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$q_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$q_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2560000}=1600$
$q_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-1600}{2*400}=\frac{-1600}{800}
=-2
$
$q_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+1600}{2*400}=\frac{1600}{800}
=2
$