You are treating the term as if it were a constant. The rule you are trying to use works when you have in the radical.
Hello, my name is Gina. I've been trying to do the following problem:
I have a hunch that my error has something to do with me not using exponents properly... but I'm not spotting it. I thought a fresh pair of eyes would help. ^_^
Anyway, if you could please tell me what I'm doing wrong with "my" method, I'd appreciate it.