I can do that.
It is a simple typo on Sedra and Smith's part.
There is a dependent voltage source in that provlem that is confusing and bemusing to you. Even so, the applied source method you are using is a clunky way to do it, especially when you have a dependent source.
You need to use a relatively unknown theorem called by different names, two of which are the General Immittance Theorem (GIT) or the Port Immittance Theorem (PIT). It basically states that in a linear circuit, if you know the transfer function between two ports, you can easily find the input and output immittance between those two ports. The theorem works because of Tellegen's theorem. I can prove it if anybody really gives a damn.
Anyway, the theorem says that the transfer function has to include the source immittance of the source and the load immittance of output. Then you find the -Rs solution of the denominator, and that gives you the input impedance. Similarly, find the -RL solution of the denominator, and that gives you the output immittance. Unless the circuit is complicated, it can be done by inspection. OK, let's see how it works. The first line of the attachment displays the input and output functions . Lines 2 and 3 show the solutions of Vo and Vi. Line 4 shows the transfer function. Examine the denominator of the transfer function. It has every parameter that affects the input and output immittance. Then we set the denominator to zero and find -RL, the output impedance. It is ro||R22 . Adding RL to it gives all three resistors in parallel. Since Rs shows up as a single term with no coefficients, you can just put your finger over the Rs term, and read the input immittance as the sum of the remaining terms.
View attachment 26801
This theorem works for any transfer function, V/V, V/I, I/I, I/V. It doesn't matter whether you represent the parameters in Laplace, Steinmetz, or any other representation you can imagine. It also does away with the angst of dependent sources. As long as you can write a transfer function for a linear circuit, you can find the input and output immittances. So GIT with with the problem and use the PIT. As always, ask if you have any questions about this method.
Ratch