I got the following two questions wrong. What are the correct answers and why?

Incorrect: 0/8 Pts

Which of the following functions f: R Z are not one to one?

f(x) = ceiling(x+1/2) + floor(x - 1/2)

f(x) = floor(x)

f(x) = ceiling(x)

Incorrect: 0/8 Pts

Which of the following functions functions f: Z Z are not onto?

f(x) = x + 1

f(x) = x^2

f(x) = 2x

f(x) = floor(x/2)