Chapter 7, Problem 7.42P

(a)

To determine

Obtain an expression for $\langle \frac{1}{r}\rangle$ and check whether the result is same as that of equation 7.58.

(b)

To determine

Obtain an expression for $\langle \frac{1}{r^2}\rangle$ by substituting $l$ for $\lambda$ check whether the result is same as that of equation 7.57.