$$ $𝑎=𝑏$ $$ $$\left(\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right)=\{\begin{array}{cc}1\hfill & \text{if <math xmlns:tex="http://typesetting.eu/2021/LuaMathML" xmlns="http://www.w3.org/1998/Math/MathML"> <mi tex:family="1">𝑎</mi> <mo lspace="0.278em" rspace="0.278em" tex:class="rel">=</mo> <mi tex:family="1">𝑏</mi> </math>}\hfill \\ 2\hfill & \text{else}\hfill \end{array}$$ $$𝑥=\frac{-𝑏\pm \sqrt{{𝑏}^2-4𝑎𝑐}}{2𝑎}.$$ $𝑏$ $$\sum _{𝑎}\underset{\_}{𝑐}\stackrel{\_}{𝑏}{𝑐}^{\mathrm{\prime }}$$ $\mathrm{s}\mathrm{i}\mathrm{n}(𝑥)-\mathrm{s}\mathrm{i}\mathrm{n}(𝑥+2𝜋)=0$