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𝑥1^2+𝑥2^2+5𝑥32−6𝑥1𝑥2+2𝑥1𝑥3−2𝑥2𝑥3 canonical form

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  2     2                                          
x1  + x2  + 5*x32 - 6*x1*x2 - 2*x2*x3 + 2*x1*x3 = 0
$$x_{1}^{2} - 6 x_{1} x_{2} + 2 x_{1} x_{3} + x_{2}^{2} - 2 x_{2} x_{3} + 5 x_{32} = 0$$
x1^2 - 6*x1*x2 + 2*x1*x3 + x2^2 - 2*x2*x3 + 5*x32 = 0
Invariants method
Given equation of the surface of 2-order:
$$x_{1}^{2} - 6 x_{1} x_{2} + 2 x_{1} x_{3} + x_{2}^{2} - 2 x_{2} x_{3} + 5 x_{32} = 0$$
This equation looks like:
$$a_{11} x_{32}^{2} + 2 a_{12} x_{3} x_{32} + 2 a_{13} x_{2} x_{32} + 2 a_{14} x_{32} + a_{22} x_{3}^{2} + 2 a_{23} x_{2} x_{3} + 2 a_{24} x_{3} + a_{33} x_{2}^{2} + 2 a_{34} x_{2} + a_{44} = 0$$
where
$$a_{11} = 0$$
$$a_{12} = 0$$
$$a_{13} = 0$$
$$a_{14} = \frac{5}{2}$$
$$a_{22} = 0$$
$$a_{23} = -1$$
$$a_{24} = x_{1}$$
$$a_{33} = 1$$
$$a_{34} = - 3 x_{1}$$
$$a_{44} = x_{1}^{2}$$
The invariants of the equation when converting coordinates are determinants:
$$I_{1} = a_{11} + a_{22} + a_{33}$$
     |a11  a12|   |a22  a23|   |a11  a13|
I2 = |        | + |        | + |        |
     |a12  a22|   |a23  a33|   |a13  a33|

$$I_{3} = \left|\begin{matrix}a_{11} & a_{12} & a_{13}\\a_{12} & a_{22} & a_{23}\\a_{13} & a_{23} & a_{33}\end{matrix}\right|$$
$$I_{4} = \left|\begin{matrix}a_{11} & a_{12} & a_{13} & a_{14}\\a_{12} & a_{22} & a_{23} & a_{24}\\a_{13} & a_{23} & a_{33} & a_{34}\\a_{14} & a_{24} & a_{34} & a_{44}\end{matrix}\right|$$
$$I{\left(\lambda \right)} = \left|\begin{matrix}a_{11} - \lambda & a_{12} & a_{13}\\a_{12} & a_{22} - \lambda & a_{23}\\a_{13} & a_{23} & a_{33} - \lambda\end{matrix}\right|$$
     |a11  a14|   |a22  a24|   |a33  a34|
K2 = |        | + |        | + |        |
     |a14  a44|   |a24  a44|   |a34  a44|

     |a11  a12  a14|   |a22  a23  a24|   |a11  a13  a14|
     |             |   |             |   |             |
K3 = |a12  a22  a24| + |a23  a33  a34| + |a13  a33  a34|
     |             |   |             |   |             |
     |a14  a24  a44|   |a24  a34  a44|   |a14  a34  a44|

substitute coefficients
$$I_{1} = 1$$
     |0  0|   |0   -1|   |0  0|
I2 = |    | + |      | + |    |
     |0  0|   |-1  1 |   |0  1|

$$I_{3} = \left|\begin{matrix}0 & 0 & 0\\0 & 0 & -1\\0 & -1 & 1\end{matrix}\right|$$
$$I_{4} = \left|\begin{matrix}0 & 0 & 0 & \frac{5}{2}\\0 & 0 & -1 & x_{1}\\0 & -1 & 1 & - 3 x_{1}\\\frac{5}{2} & x_{1} & - 3 x_{1} & x_{1}^{2}\end{matrix}\right|$$
$$I{\left(\lambda \right)} = \left|\begin{matrix}- \lambda & 0 & 0\\0 & - \lambda & -1\\0 & -1 & 1 - \lambda\end{matrix}\right|$$
     | 0   5/2|   |0   x1 |   |  1    -3*x1|
     |        |   |       |   |            |
K2 = |       2| + |      2| + |          2 |
     |5/2  x1 |   |x1  x1 |   |-3*x1   x1  |
           

     | 0   0   5/2|   |0    -1     x1  |   | 0     0     5/2 |
     |            |   |                |   |                 |
     | 0   0   x1 |   |-1    1    -3*x1|   | 0     1    -3*x1|
K3 = |            | + |                | + |                 |
     |           2|   |              2 |   |               2 |
     |5/2  x1  x1 |   |x1  -3*x1   x1  |   |5/2  -3*x1   x1  |
           

$$I_{1} = 1$$
$$I_{2} = -1$$
$$I_{3} = 0$$
$$I_{4} = \frac{25}{4}$$
$$I{\left(\lambda \right)} = - \lambda^{3} + \lambda^{2} + \lambda$$
$$K_{2} = - 9 x_{1}^{2} - \frac{25}{4}$$
$$K_{3} = 4 x_{1}^{2} - \frac{25}{4}$$
Because
$$I_{3} = 0 \wedge I_{2} \neq 0 \wedge I_{4} \neq 0$$
then by type of surface:
you need to
Make the characteristic equation for the surface:
$$- I_{1} \lambda^{2} + I_{2} \lambda - I_{3} + \lambda^{3} = 0$$
or
$$\lambda^{3} - \lambda^{2} - \lambda = 0$$
$$\lambda_{1} = \frac{1}{2} - \frac{\sqrt{5}}{2}$$
$$\lambda_{2} = \frac{1}{2} + \frac{\sqrt{5}}{2}$$
$$\lambda_{3} = 0$$
then the canonical form of the equation will be
$$\tilde x2 \cdot 2 \sqrt{\frac{\left(-1\right) I_{4}}{I_{2}}} + \left(\tilde x3^{2} \lambda_{2} + \tilde x32^{2} \lambda_{1}\right) = 0$$
and
$$- \tilde x2 \cdot 2 \sqrt{\frac{\left(-1\right) I_{4}}{I_{2}}} + \left(\tilde x3^{2} \lambda_{2} + \tilde x32^{2} \lambda_{1}\right) = 0$$
$$5 \tilde x2 + \tilde x3^{2} \left(\frac{1}{2} + \frac{\sqrt{5}}{2}\right) + \tilde x32^{2} \left(\frac{1}{2} - \frac{\sqrt{5}}{2}\right) = 0$$
and
$$- 5 \tilde x2 + \tilde x3^{2} \left(\frac{1}{2} + \frac{\sqrt{5}}{2}\right) + \tilde x32^{2} \left(\frac{1}{2} - \frac{\sqrt{5}}{2}\right) = 0$$
$$- 2 \tilde x2 + \left(- \frac{\tilde x3^{2}}{\frac{5}{2} \frac{1}{\frac{1}{2} + \frac{\sqrt{5}}{2}}} + \frac{\tilde x32^{2}}{\frac{5}{2} \frac{1}{- \frac{1}{2} + \frac{\sqrt{5}}{2}}}\right) = 0$$
and
$$2 \tilde x2 + \left(- \frac{\tilde x3^{2}}{\frac{5}{2} \frac{1}{\frac{1}{2} + \frac{\sqrt{5}}{2}}} + \frac{\tilde x32^{2}}{\frac{5}{2} \frac{1}{- \frac{1}{2} + \frac{\sqrt{5}}{2}}}\right) = 0$$
this equation is fora type hyperbolic paraboloid
- reduced to canonical form