Assignment Question :

A. Let A = {x N | x = 2a, for some a from N and 10 x 20}

B = {x N | x = 5a, for some a from N and 10 x 20}

1. Describe each of A and B using roster method
2. Find A B, A B , A - B, B - A, and A B then use set builder method to describe A B
3. Find |A B| and P (A B)

B. Why is f not a function from R to R if

1. f(x) = 1 / x
2. f(x) = x
3. f(x) = (x^2 + 1)

C. Determine with proper justification whether each of these functions is a one to one, onto ,or a bijection from R to R

1. f(x) = 3x - 2
2. f(x) = x^2 - 1