(x)=3x^2-27=0

Solution for (x)=3x^2-27=0 equation:

(x)=3x^2-27=0

We move all terms to the left:

(x)-(3x^2-27)=0

We get rid of parentheses

-3x^2+x+27=0

a = -3; b = 1; c = +27;
Δ = b2-4ac
Δ = 12-4·(-3)·27
Δ = 325
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:

$\sqrt{\Delta}=\sqrt{325}=\sqrt{25*13}=\sqrt{25}*\sqrt{13}=5\sqrt{13}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-5\sqrt{13}}{2*-3}=\frac{-1-5\sqrt{13}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+5\sqrt{13}}{2*-3}=\frac{-1+5\sqrt{13}}{-6}
$