wheetabix

Sat, 02 May 2026 23:32:37 +0000

404 n-1nn \dfrac {\ln \left ( n\right) -\ln \left ( n-1\right) } {n-\left ( n-1\right) } \left ( \ln n\right). 1+1=2 1 0 0 Is there a formal proof for $(-1) \\times (-1) = 1$? It's a fundamental formula not only in arithmetic but also in the whole of math. Is there a proof for it or is it just assumed?