3x+27=9x+x^2

Solution for 3x+27=9x+x^2 equation:

3x+27=9x+x^2

We move all terms to the left:

3x+27-(9x+x^2)=0

We get rid of parentheses

-x^2-9x+3x+27=0

We add all the numbers together, and all the variables

-1x^2-6x+27=0

a = -1; b = -6; c = +27;
Δ = b2-4ac
Δ = -62-4·(-1)·27
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-12}{2*-1}=\frac{-6}{-2}
=+3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+12}{2*-1}=\frac{18}{-2}
=-9
$