graphing with out an equasion...y=-x

Answer 1

you have an equation, y = -x.

Answer 2

In google type:
functions graphs online

When you see list of results click on:
rechneronline.de/function-graphs/

When page be open in blue recatacangle type:

-x

Then click option Draw

Answer 3

Make that website
http://rechneronline.de/function-graphs/

Excellent choice.

You can plot three functions on the same graph there.