1/3x=x+6

Solution for 1/3x=x+6 equation:

1/3x=x+6

We move all terms to the left:

1/3x-(x+6)=0


Domain of the equation: 3x!=0

x!=0/3

x!=0

x∈R


We get rid of parentheses

1/3x-x-6=0

We multiply all the terms by the denominator


-x*3x-6*3x+1=0

Wy multiply elements

-3x^2-18x+1=0

a = -3; b = -18; c = +1;
Δ = b2-4ac
Δ = -182-4·(-3)·1
Δ = 336
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:

$\sqrt{\Delta}=\sqrt{336}=\sqrt{16*21}=\sqrt{16}*\sqrt{21}=4\sqrt{21}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-4\sqrt{21}}{2*-3}=\frac{18-4\sqrt{21}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+4\sqrt{21}}{2*-3}=\frac{18+4\sqrt{21}}{-6}
$