[racket] Am I Missing Something? [HtDP 31.3.1]

Ok, I see the problem, now. (When I tried earlier, I was confused about
what I should be looking for.)

Racket sets the x87 control word to use double precision instead of
extended precision. That setting apparently interferes with the pow()
C library function.

Mac library functions use SSE for floating point, so the x87 control
setting wouldn't matter for pow().