#### Answer

The graph of an equation is symmetric with respect to the y-axis if substituting \[-x\text{ for }x\] in the equation results in an equivalent equation.

#### Work Step by Step

We know that if the graph of a function is symmetric about y-axis, then it is an even function and if replacement of $x$ by $-x$, there will be no effect on the function.
For example,
\[y={{x}^{2}}+2\]
Replace $x$ by $-x$:
\[\begin{align}
& y={{\left( -x \right)}^{2}}+2 \\
& y={{x}^{2}}+2 \\
\end{align}\]
Thus, this equation is an equivalent equation. So, the graph will be symmetric with respect to the y-axis.