It did abysmally at this one, but once I explained it, it echoed my explanation in more words - which is all it’s really doing here anyway. why might this joke

It did abysmally at this one, but once I explained it, it echoed my explanation in more words - which is all it’s really doing here anyway. why might this joke be funny? Two mathematicians walk into a bar. One laments that young people don’t study math any more. The other disagrees. When the first goes to the bathroom, the second calls over the waitress. He says, “will you help me settle a dispute with my friend?” She agrees. He tells her, “I’m going to ask you a question, and you reply with ‘one third x cubed’, got it?” She repeats the phrase slowly, as if confused, “one third x cubed.” “Okay good , here he comes now”. When the first mathematician returns to the table the second says, “I’m going to disprove your claim that young people don’t study math any more. Miss, what is the integral of x squared?” The waitress hems and haws for a minute then repeats what she was told, “one third x cubed” and then goes on to add “plus a constant”.