x=1/3x+7

Solution for x=1/3x+7 equation:

x=1/3x+7

We move all terms to the left:

x-(1/3x+7)=0


Domain of the equation: 3x+7)!=0

x∈R


We get rid of parentheses

x-1/3x-7=0

We multiply all the terms by the denominator


x*3x-7*3x-1=0

Wy multiply elements

3x^2-21x-1=0

a = 3; b = -21; c = -1;
Δ = b2-4ac
Δ = -212-4·3·(-1)
Δ = 453
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-\sqrt{453}}{2*3}=\frac{21-\sqrt{453}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+\sqrt{453}}{2*3}=\frac{21+\sqrt{453}}{6}
$