(3x)^2=729

Solution for (3x)^2=729 equation:

(3x)^2=729

We move all terms to the left:

(3x)^2-(729)=0

a = 3; b = 0; c = -729;
Δ = b2-4ac
Δ = 02-4·3·(-729)
Δ = 8748
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:

$\sqrt{\Delta}=\sqrt{8748}=\sqrt{2916*3}=\sqrt{2916}*\sqrt{3}=54\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-54\sqrt{3}}{2*3}=\frac{0-54\sqrt{3}}{6}
=-\frac{54\sqrt{3}}{6}
=-9\sqrt{3}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+54\sqrt{3}}{2*3}=\frac{0+54\sqrt{3}}{6}
=\frac{54\sqrt{3}}{6}
=9\sqrt{3}
$