If $$E$$ denotes expectation, the variance of a random variable $$X$$ is given by

Consider the function $$\,f\left( x \right) = {x^2} - x - 2.\,$$ The maximum value of $$f(x)$$ in the closed interval $$\left[ { - 4,4} \right]\,$$

For $$\left| x \right| < < 1,\,\cot \,h\left( x \right)\,\,\,$$ can be approximated as

For the function $${e^{ - x}},$$ the linear approximation around $$x=2$$ is