How Do You Write Maths In Stack Exchange?

How Do You Write Maths In Stack Exchange? Inline formulas are surrounded by single dollar signs. For example, $f(x) = ax^2 + bx + c$ renders as f(x)=ax2+bx+c. Block formulas are surrounded by double dollar signs. For example, $$x = frac{-b pm sqrt{b^2 – 4ac} }{2a}$$ renders, on a separate line, as x=−b±√b2−4ac2a. How do