X*2x=66

Solution for X*2x=66 equation:

X*2X=66

We move all terms to the left:

X*2X-(66)=0

Wy multiply elements

2X^2-66=0

a = 2; b = 0; c = -66;
Δ = b2-4ac
Δ = 02-4·2·(-66)
Δ = 528
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:

$\sqrt{\Delta}=\sqrt{528}=\sqrt{16*33}=\sqrt{16}*\sqrt{33}=4\sqrt{33}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{33}}{2*2}=\frac{0-4\sqrt{33}}{4}
=-\frac{4\sqrt{33}}{4}
=-\sqrt{33}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{33}}{2*2}=\frac{0+4\sqrt{33}}{4}
=\frac{4\sqrt{33}}{4}
=\sqrt{33}
$