3(3x2)=21

Solution for 3(3x2)=21 equation:

3(3x^2)=21

We move all terms to the left:

3(3x^2)-(21)=0

a = 33; b = 0; c = -21;
Δ = b2-4ac
Δ = 02-4·33·(-21)
Δ = 2772
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:

$\sqrt{\Delta}=\sqrt{2772}=\sqrt{36*77}=\sqrt{36}*\sqrt{77}=6\sqrt{77}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-6\sqrt{77}}{2*33}=\frac{0-6\sqrt{77}}{66}
=-\frac{6\sqrt{77}}{66}
=-\frac{\sqrt{77}}{11}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+6\sqrt{77}}{2*33}=\frac{0+6\sqrt{77}}{66}
=\frac{6\sqrt{77}}{66}
=\frac{\sqrt{77}}{11}
$