Answer to Question #1839 in Discrete Mathematics for Gloria Parlatore

Question

Give examples of functions N to N that are:
a) one-to-one but NOT onto
b) onto but NOT one-to-one
c) both
d) neither one-to-one nor onto

Answer 1

a) for example, exponenta: e^x;
b) x = b,
c) straight line (y = ax + b, if a<>0)
d) parabola, y= x²; or modulus: y = |x+2|.