X*2x-2=84

Solution for X*2x-2=84 equation:

X*2X-2=84

We move all terms to the left:

X*2X-2-(84)=0

We add all the numbers together, and all the variables

X*2X-86=0

Wy multiply elements

2X^2-86=0

a = 2; b = 0; c = -86;
Δ = b2-4ac
Δ = 02-4·2·(-86)
Δ = 688
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:

$\sqrt{\Delta}=\sqrt{688}=\sqrt{16*43}=\sqrt{16}*\sqrt{43}=4\sqrt{43}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{43}}{2*2}=\frac{0-4\sqrt{43}}{4}
=-\frac{4\sqrt{43}}{4}
=-\sqrt{43}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{43}}{2*2}=\frac{0+4\sqrt{43}}{4}
=\frac{4\sqrt{43}}{4}
=\sqrt{43}
$