The eigen values of $$\left[ {\matrix{ 1 & 1 & 1 \cr 1 & 1 & 1 \cr 1 & 1 & 1 \cr } } \right]$$ are

In the Gauss - elimination for a solving system of linear algebraic equations, triangularization leads to

If a function is continuous at a point its first derivative

The expression curl $$\left( {grad\,f} \right)$$ where $$f$$ is a scalar function is