Integration by SubstitutionSUGGESTED REFERENCE MATERIAL:As you work through the problems listed below, you should reference Chapter 5.3 of the rec-ommended textbook (or the equivalent chapter in your alternative textbook/online resource)and your lecture notes.EXPECTED SKILLS:•Know how to simplify a “complicated integral” to a known form by making an appro-priate substitution of variables.PRACTICE PROBLEMS:For problems 1-21, evaluate the given indefinite integral and verify that youranswer is correct by differentiation.1.Z3x2(x3+ 3)3dx2.Z55x+ 3dx3.Z2xcos (x2)dx4.Z4x(x2+ 6)2dx5.Zsec (4x) tan (4x)dx6.Z(3x-5)9dx7.Ze-2xdx8.Zsinxcosx1 + sin2xdx9.Zcscx2cotx2dx10.Z-3x3√1-x4dx11.Ze√x√x-14cos 4xdx1