(x+x)*2x=210

Solution for (x+x)*2x=210 equation:

(x+x)*2x=210

We move all terms to the left:

(x+x)*2x-(210)=0

We add all the numbers together, and all the variables

(+2x)*2x-210=0

We multiply parentheses

4x^2-210=0

a = 4; b = 0; c = -210;
Δ = b2-4ac
Δ = 02-4·4·(-210)
Δ = 3360
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:

$\sqrt{\Delta}=\sqrt{3360}=\sqrt{16*210}=\sqrt{16}*\sqrt{210}=4\sqrt{210}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{210}}{2*4}=\frac{0-4\sqrt{210}}{8}
=-\frac{4\sqrt{210}}{8}
=-\frac{\sqrt{210}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{210}}{2*4}=\frac{0+4\sqrt{210}}{8}
=\frac{4\sqrt{210}}{8}
=\frac{\sqrt{210}}{2}
$