1.8.1 Quadratic forms

Problem: Investigate the quadratic form for signdefiniteness, bring it to the canonical form by orthogonal transformation and write down the transition matrix. \[ \begin{array}{l} f\left(x_{1}, x_{2} x_{3}\right)=3 x_{1}{ }^{2}+x_{2}{ }^{2}-\frac{3}{2} x_{3}{ }^{2}+2 \sqrt{3} x_{1} x_{2}- \\ -x_{1} x_{3}+\sqrt{3} x_{2} x_{3} . \end{array} \]