To place something written in TeX in math mode use signs to enclose the math you want to display. There are three methods for displaying formulas in Wikipedia. In-line maths elements can be set with a different style.
If you want your equation to get a number use the label option.
When given it selects an internal label for the equation by which it can be cross-referenced and causes an equation number to be issued. AMS Math package. Just do a search for latex online editor Math equation online or latex to image and there will be plenty. Raw HTML HTML with math templates abbreviated here as math and a subset of LaTeX implemented with the HTML markup referred to as LaTeX in this article.