SOLVED:Each of Exercises 63-66 gives a function f(x, y, z) and a positive number \epsilon . In each exercise, show that there exists a \delta>0 such that for all (x, y, z) , \quad \sqrt{x^{2}+y^{2}+z^{2}}<\delta \Rightarrow|f(x, y, z)-f(0,0,0)|<\epsilon f(x, y, z)=x y z, \quad \epsilon=0.008