$\mathbf{ax^2+bx+c}$
$\sqrt{ab}$、$\sqrt[n]{ab}$、$\log_{a}{b}$、$\lg{ab}$、$a^{b}$、$a_{b}$、$x_a^b$、$\int$、$\int_{a}^{b}$、$\oint$、$\oint_a^b$、$\sum$、$\sum_a^b$、$\coprod$、$\coprod_a^b$、$\prod$、$\prod_a^b$、$\bigcap$、$\bigcap_a^b$、$\bigcup$、$\bigcup_a^b$、$\bigsqcup$、$\bigsqcup_a^b$、$\bigvee$、$\bigvee_a^b$、$\bigwedge$、$\bigwedge_a^b$、$\widetilde{ab}$、$\widehat{ab}$、$\overleftarrow{ab}$、$\overrightarrow{ab}$、$\overbrace{ab}$、$\underbrace{ab}$、$\underline{ab}$、$\overline{ab}$、$\frac{ab}{cd}$、$\frac{\partial a}{\partial b}$、$\frac{\text{d}x}{\text{d}y}$、$\lim_{a \rightarrow b}$