Let r(x) = - u''(x) / u'(x) be the absolute risk aversion coefficient and rr(x) = xr(x) the relative risk aversion coefficient. a) Show that for u(x) = -e^-A(x), the coefficient of absolute risk aversion is constant and equal to A.

b) Show that for u(x) = (x^1-a ) / (1-a) , the coefficient of relative risk aversion is constant and equal to a