give an example

$$
\frac{\partial y}{\partial x_1} + \frac{\partial y}{\partial x_2} \\
\frac{\mathrm{d}y}{\mathrm{d}x_1} + \frac{\mathrm{d}y}{\mathrm{d}x_2}
$$

The display effect is as follows:
0

∂

y

∂

x

one

+

∂

y

∂

x

two

\frac{\partial y}{\partial x_ 1} + \frac{\partial y}{\partial x_ 2}

∂x1​∂y​+∂x2​∂y​

d

y

d

x

+

d

z

d

x

\frac{\mathrm{d}y}{\mathrm{d}x} + \frac{\mathrm{d}z}{\mathrm{d}x}

dxdy​+dxdz​