Inline and display equation font size

Question

I need the display equation fontsize 1pt smaller than the normal text, but inline equation remain same as text font size. how to handle this in latex anyone help on this

thanks in advance

Answer 1

You can define a new environment.

\documentclass[11pt]{article}
\usepackage{amsmath}
\usepackage{environ}
\NewEnviron{myequation}{%
\par\vspace{-\baselineskip}
\small
\begin{equation}%
\BODY
\end{equation}
}

\begin{document}
\noindent Some text here $y=x$ Some text here Some text here Some text here Some text here Some text here Some text here Some text here Some text here Some text here
  \begin{myequation}%
  f(y) = ya \times k^{y} %
\end{myequation}
Some text here $f(y)=0$
\end{document}

Answer 2

Define a newcommand for setting equation font size.

\documentclass[10pt]{article}
\newcommand{\se}[1]{\fontsize{9}{0} % 1pt smaller then normal text. Set it whatever you want
\begin{equation}
{#1}
\end{equation}
\fontsize{10}{0}
}

\begin{document}

This is $f(x)=g(x)$ an inline equation.

 This is display mode equation. \se{\lim_{x \to \infty} \exp(-x) = 0}

 This is another $y=\sin (x)$  inline equation.

\end{document}