You can’t use `\eqno’ in math mode
Description
\eqno assigns an equation number and can only be used in display math ($$), not inline math ($).
Remediation
Use display math: \[ x \tag{1} \] or \begin{equation}.
\eqno assigns an equation number and can only be used in display math ($$), not inline math ($).
Use display math: \[ x \tag{1} \] or \begin{equation}.