Post Closed as "no longer relevant" by Robin Chapman, Akhil Mathew, Yemon Choi, Qiaochu Yuan, Pete L. Clark

show/hide this revision's text 2 tag
show/hide this revision's text 1 [made Community Wiki]

What's your favorite equation, formula, identity or inequality?

Certain formulas I really enjoy looking at like the Euler-Maclaurin formula or the Leibniz integral rule. What's your favorite equation, formula, identity or inequality?