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x^2+y^2-6x+4y-12=0 canonical form

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The solution

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       2    2                
-12 + x  + y  - 6*x + 4*y = 0
$$x^{2} - 6 x + y^{2} + 4 y - 12 = 0$$
x^2 - 6*x + y^2 + 4*y - 12 = 0
Detail solution
Given line equation of 2-order:
$$x^{2} - 6 x + y^{2} + 4 y - 12 = 0$$
This equation looks like:
$$a_{11} x^{2} + 2 a_{12} x y + 2 a_{13} x + a_{22} y^{2} + 2 a_{23} y + a_{33} = 0$$
where
$$a_{11} = 1$$
$$a_{12} = 0$$
$$a_{13} = -3$$
$$a_{22} = 1$$
$$a_{23} = 2$$
$$a_{33} = -12$$
To calculate the determinant
$$\Delta = \left|\begin{matrix}a_{11} & a_{12}\\a_{12} & a_{22}\end{matrix}\right|$$
or, substitute
$$\Delta = \left|\begin{matrix}1 & 0\\0 & 1\end{matrix}\right|$$
$$\Delta = 1$$
Because
$$\Delta$$
is not equal to 0, then
find the center of the canonical coordinate system. To do it, solve the system of equations
$$a_{11} x_{0} + a_{12} y_{0} + a_{13} = 0$$
$$a_{12} x_{0} + a_{22} y_{0} + a_{23} = 0$$
substitute coefficients
$$x_{0} - 3 = 0$$
$$y_{0} + 2 = 0$$
then
$$x_{0} = 3$$
$$y_{0} = -2$$
Thus, we have the equation in the coordinate system O'x'y'
$$a'_{33} + a_{11} x'^{2} + 2 a_{12} x' y' + a_{22} y'^{2} = 0$$
where
$$a'_{33} = a_{13} x_{0} + a_{23} y_{0} + a_{33}$$
or
$$a'_{33} = - 3 x_{0} + 2 y_{0} - 12$$
$$a'_{33} = -25$$
then equation turns into
$$x'^{2} + y'^{2} - 25 = 0$$
Given equation is circle
        2           2    
\tilde x    \tilde y     
--------- + --------- = 1
      2           2      
  / 1\        / 1\       
  \5 /        \5 /       

- reduced to canonical form
The center of canonical coordinate system at point O
(3, -2)

Basis of the canonical coordinate system
$$\vec e_1 = \left( 1, \ 0\right)$$
$$\vec e_2 = \left( 0, \ 1\right)$$
Invariants method
Given line equation of 2-order:
$$x^{2} - 6 x + y^{2} + 4 y - 12 = 0$$
This equation looks like:
$$a_{11} x^{2} + 2 a_{12} x y + 2 a_{13} x + a_{22} y^{2} + 2 a_{23} y + a_{33} = 0$$
where
$$a_{11} = 1$$
$$a_{12} = 0$$
$$a_{13} = -3$$
$$a_{22} = 1$$
$$a_{23} = 2$$
$$a_{33} = -12$$
The invariants of the equation when converting coordinates are determinants:
$$I_{1} = a_{11} + a_{22}$$
     |a11  a12|
I2 = |        |
     |a12  a22|

$$I_{3} = \left|\begin{matrix}a_{11} & a_{12} & a_{13}\\a_{12} & a_{22} & a_{23}\\a_{13} & a_{23} & a_{33}\end{matrix}\right|$$
$$I{\left(\lambda \right)} = \left|\begin{matrix}a_{11} - \lambda & a_{12}\\a_{12} & a_{22} - \lambda\end{matrix}\right|$$
     |a11  a13|   |a22  a23|
K2 = |        | + |        |
     |a13  a33|   |a23  a33|

substitute coefficients
$$I_{1} = 2$$
     |1  0|
I2 = |    |
     |0  1|

$$I_{3} = \left|\begin{matrix}1 & 0 & -3\\0 & 1 & 2\\-3 & 2 & -12\end{matrix}\right|$$
$$I{\left(\lambda \right)} = \left|\begin{matrix}1 - \lambda & 0\\0 & 1 - \lambda\end{matrix}\right|$$
     |1   -3 |   |1   2 |
K2 = |       | + |      |
     |-3  -12|   |2  -12|

$$I_{1} = 2$$
$$I_{2} = 1$$
$$I_{3} = -25$$
$$I{\left(\lambda \right)} = \lambda^{2} - 2 \lambda + 1$$
$$K_{2} = -37$$
Because
$$I_{2} > 0 \wedge I_{1} I_{3} < 0$$
then by line type:
this equation is of type : circle
Make the characteristic equation for the line:
$$- I_{1} \lambda + I_{2} + \lambda^{2} = 0$$
or
$$\lambda^{2} - 2 \lambda + 1 = 0$$
$$\lambda_{1} = 1$$
$$\lambda_{2} = 1$$
then the canonical form of the equation will be
$$\tilde x^{2} \lambda_{1} + \tilde y^{2} \lambda_{2} + \frac{I_{3}}{I_{2}} = 0$$
or
$$\tilde x^{2} + \tilde y^{2} - 25 = 0$$
        2           2    
\tilde x    \tilde y     
--------- + --------- = 1
      2           2      
  / 1\        / 1\       
  \5 /        \5 /       

- reduced to canonical form