I am in taking Trigonometry right now, and we are working on finding the inverse of functions. To do this, we occasionally have to limit the domain so as to make the function pass the horizontal line test. I can seem to figure out how to correctly do this. For example, I am going to use the function y=x² where x≤0. I have tried typing y=x²(x≤0), but it results in the correct shape left of x=0, but then it has a horizontal line at y=0. I can seem to be able to remove that horizontal line. I understand the math behind the horizontal line. It results from the expression (x≤0) outputting 0 when the function passes the y-axis. Can somebody please show how to write the equation correctly? Thanks!

Limiting The Domain When Graphing