There are two important thing in this quesion which can create problem for us. One is exponent is negative. And second is what is base under the exponent 3 or -3.

The solution of these two confusions is as following
1-I already mention in negative exponent related articles that first convert the negative exponent into positive exponent.
2-I have also explained that the base with a negative sign without paratheses mean exponent is not on negative sign.