Question: Use integration by substitution to find

(a) \(\int{\left( 3{{x}^{2}}-1 \right){{\left( {{x}^{3}}-x \right)}^{5}}dx}\)

(b) \(\int{3x{{e}^{{{x}^{2}}+1}}dx}\)

(c) \(\int{x\sqrt{3{{x}^{2}}-1}dx}\)

(d) \(\int{\frac{dx}{3-x}}\)