4. Consider the integral /9 "3_\\/E d3. 1 x/rE (a) Provide three different (and nonidentity} i.e., not a = m) valid u~substitutions that can be used to evaluate this integral. Make sure to show that your substitution is valid. That is, perform your change of variable but do n_ot evaluate the resulting integral. (b) Complete the evaluation of this integral for one of your usubstitutions from part (a)