2400=3x*4x

Solution for 2400=3x*4x equation:

2400=3x*4x

We move all terms to the left:

2400-(3x*4x)=0

We add all the numbers together, and all the variables

-(+3x*4x)+2400=0

We get rid of parentheses

-3x*4x+2400=0

Wy multiply elements

-12x^2+2400=0

a = -12; b = 0; c = +2400;
Δ = b2-4ac
Δ = 02-4·(-12)·2400
Δ = 115200
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:

$\sqrt{\Delta}=\sqrt{115200}=\sqrt{57600*2}=\sqrt{57600}*\sqrt{2}=240\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-240\sqrt{2}}{2*-12}=\frac{0-240\sqrt{2}}{-24}
=-\frac{240\sqrt{2}}{-24}
=-\frac{10\sqrt{2}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+240\sqrt{2}}{2*-12}=\frac{0+240\sqrt{2}}{-24}
=\frac{240\sqrt{2}}{-24}
=\frac{10\sqrt{2}}{-1}
$