There are several errors in the induction handout. 

Line 4 of example 1 on page 2. 
Reads .....=N^2+N+2N
Should read ....=N^2-N+2N

Line 5 of example 1 on page 2. 
Reads ....N^2+N....
Should read  ....N^2-N....

Line 1 of the hint in exercise 3 part a) on page 3.
Reads ....left-hand....
Should read .....right-hand.....

Line 5 of exercise 3 part b) on page 3.
Reads ....should write (x+y)^(N+1)=(x+1)(x+y)^N....
Should read ....should write (x+y)^(N+1)=(x+y)(x+y)^N....