well.. for the equation x= 3.5, let's take a look at its values
[tex]\bf \begin{array}{lrlll}
x&y\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
3.5&-\infty\\
3.5&-1,000,000\\
3.5&-1,000\\
3.5&-100\\
3.5&-10\\
3.5&-1\\
3.5&0\\
3.5&1\\
3.5&10\\
3.5&100\\
3.5&1,000\\
3.5&1,000,000\\
3.5&1+\infty
\end{array}[/tex]
so.. notice.. no matter what "y" is, "x" will always be 3.5,
so is really just a horizontal line, thus, look at the picture below
