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3*x^2-7*y^2+3*z^2+8*x*y-8*x*z-8*y*z+10*x-14*y-6*z-8=0 canonical form

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               2            2      2                                   
-8 - 14*y - 7*y  - 6*z + 3*x  + 3*z  + 10*x - 8*x*z - 8*y*z + 8*x*y = 0
$$3 x^{2} + 8 x y - 8 x z + 10 x - 7 y^{2} - 8 y z - 14 y + 3 z^{2} - 6 z - 8 = 0$$
3*x^2 + 8*x*y - 8*x*z + 10*x - 7*y^2 - 8*y*z - 14*y + 3*z^2 - 6*z - 8 = 0
Invariants method
Given equation of the surface of 2-order:
$$3 x^{2} + 8 x y - 8 x z + 10 x - 7 y^{2} - 8 y z - 14 y + 3 z^{2} - 6 z - 8 = 0$$
This equation looks like:
$$a_{11} x^{2} + 2 a_{12} x y + 2 a_{13} x z + 2 a_{14} x + a_{22} y^{2} + 2 a_{23} y z + 2 a_{24} y + a_{33} z^{2} + 2 a_{34} z + a_{44} = 0$$
where
$$a_{11} = 3$$
$$a_{12} = 4$$
$$a_{13} = -4$$
$$a_{14} = 5$$
$$a_{22} = -7$$
$$a_{23} = -4$$
$$a_{24} = -7$$
$$a_{33} = 3$$
$$a_{34} = -3$$
$$a_{44} = -8$$
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
$$I_{1} = -1$$
     |3  4 |   |-7  -4|   |3   -4|
I2 = |     | + |      | + |      |
     |4  -7|   |-4  3 |   |-4  3 |

$$I_{3} = \left|\begin{matrix}3 & 4 & -4\\4 & -7 & -4\\-4 & -4 & 3\end{matrix}\right|$$
$$I_{4} = \left|\begin{matrix}3 & 4 & -4 & 5\\4 & -7 & -4 & -7\\-4 & -4 & 3 & -3\\5 & -7 & -3 & -8\end{matrix}\right|$$
$$I{\left(\lambda \right)} = \left|\begin{matrix}3 - \lambda & 4 & -4\\4 & - \lambda - 7 & -4\\-4 & -4 & 3 - \lambda\end{matrix}\right|$$
     |3  5 |   |-7  -7|   |3   -3|
K2 = |     | + |      | + |      |
     |5  -8|   |-7  -8|   |-3  -8|

     |3  4   5 |   |-7  -4  -7|   |3   -4  5 |
     |         |   |          |   |          |
K3 = |4  -7  -7| + |-4  3   -3| + |-4  3   -3|
     |         |   |          |   |          |
     |5  -7  -8|   |-7  -3  -8|   |5   -3  -8|

$$I_{1} = -1$$
$$I_{2} = -81$$
$$I_{3} = 81$$
$$I_{4} = 81$$
$$I{\left(\lambda \right)} = - \lambda^{3} - \lambda^{2} + 81 \lambda + 81$$
$$K_{2} = -75$$
$$K_{3} = 162$$
Because
I3 != 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
$$\lambda^{3} + \lambda^{2} - 81 \lambda - 81 = 0$$
$$\lambda_{1} = 9$$
$$\lambda_{2} = -1$$
$$\lambda_{3} = -9$$
then the canonical form of the equation will be
$$\left(\tilde z^{2} \lambda_{3} + \left(\tilde x^{2} \lambda_{1} + \tilde y^{2} \lambda_{2}\right)\right) + \frac{I_{4}}{I_{3}} = 0$$
$$9 \tilde x^{2} - \tilde y^{2} - 9 \tilde z^{2} + 1 = 0$$
$$- \frac{\tilde x^{2}}{\left(\frac{1}{3}\right)^{2}} + \left(\frac{\tilde y^{2}}{\left(1^{-1}\right)^{2}} + \frac{\tilde z^{2}}{\left(\frac{1}{3}\right)^{2}}\right) = 1$$
this equation is fora type one-sided hyperboloid
- reduced to canonical form