The function $$f(x) = \left\{ {\matrix{ {{{{e^{3x}} - {e^{ - 5x}}} \over x},} & {if\,x \ne 0} \cr {k,} & {if\,x = 0} \cr } } \right.$$ is continuous at x = 0 for the value of k, as

If C_ij denotes the cofactor of element p_ij of the matrix $$P = \left[ {\matrix{ 1 & { - 1} & 2 \cr 0 & 2 & { - 3} \cr 3 & 2 & 4 \cr } } \right]$$, then the value of $${C_{31}}\,.\,{C_{23}}$$ is

The function $$y = {x^2}{e^{ - x}}$$ is decreasing in the interval

If R = {(x, y); x, y $$\in$$ Z, x² + y² $$\le$$ 4} is a relation in set Z, then domain of R is