X subset Y Rightarrow forall x in X. As the equation environment doesnt permit line breaks consider using a multline environment. The line after newindentedline should be indented and start in a new line.
For instance if you want an in-line mathematical element to display as a equation-like element put displaystyle before that element.
Displaystyle lim _ xto infty exp -x0. Produces code for directly embedding equations into HTML websites forums or blogs. In general the command signifies a line break and within the correct math mode environment it can start a new equation line. Again use to toggle the equation numbering.