0.64x^2-0.81=0

Solution for 0.64x^2-0.81=0 equation:

0.64x^2-0.81=0

a = 0.64; b = 0; c = -0.81;
Δ = b2-4ac
Δ = 02-4·0.64·(-0.81)
Δ = 2.0736
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{-(0)-\sqrt{2.0736}}{2*0.64}=\frac{0-\sqrt{2.0736}}{1.28}
=-\frac{\sqrt{}}{1.28}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{2.0736}}{2*0.64}=\frac{0+\sqrt{2.0736}}{1.28}
=\frac{\sqrt{}}{1.28}
$