How to use mathematical induction to prove the following questions

6 . Consider the open sentence P ( 1 ) : 9 + 13 + + ... + ( An + 5) _ _^ ^n't, where n > 1. `. Verify the implication P ( 1 ) - P ( n + 1 ) b . Is P ( n ) true for all MEN ?5. Let an be the sequence defined by a1 = 1, 02 = 8, an = an-1 + 2an-2 for n 2 3. Prove that an = 3 . 2"-1 + 2(-1)" Vn 2 1