$$ \begin{aligned}\frac{6}{(x-4)\cdot9x}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{6}{9x^2-36x}\end{aligned} $$ | |
① | $$ \left( \color{blue}{x-4}\right) \cdot 9x = 9x^2-36x $$ |