(X*2)x=168

Solution for (X*2)x=168 equation:

(X*2)X=168

We move all terms to the left:

(X*2)X-(168)=0

We add all the numbers together, and all the variables

(+X*2)X-168=0

We multiply parentheses

2X^2-168=0

a = 2; b = 0; c = -168;
Δ = b2-4ac
Δ = 02-4·2·(-168)
Δ = 1344
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:

$\sqrt{\Delta}=\sqrt{1344}=\sqrt{64*21}=\sqrt{64}*\sqrt{21}=8\sqrt{21}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-8\sqrt{21}}{2*2}=\frac{0-8\sqrt{21}}{4}
=-\frac{8\sqrt{21}}{4}
=-2\sqrt{21}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+8\sqrt{21}}{2*2}=\frac{0+8\sqrt{21}}{4}
=\frac{8\sqrt{21}}{4}
=2\sqrt{21}
$