Hello, I have a problem that wants me to find the expectation value of <r> <r^2> for the ground state of hydrogen (part a.). My friend and I already completed the exercise but i'm concerned about how we found the expectation value. Since the ground state of hydrogen is only dependent on r do we only integrate over r? I notice that if we integrate over psi and phi we will add an extra 2pi^2 multiplied with what we had previously. Any help would be appreciated: Recap- Do you integrate over all three dimensions if the wave function is only dependent on one?