Could someone please help me with the functions problem.
I know by definition:(lecture notes)
injective, or one-to-one, if different elements of X have different images under F: x1 6= x2 implies F(x1) 6= F(x2) (or equivalently, F(x1) = F(x2) implies x1 = x2).
surjective, or onto, if its range is equal to Y: that is, for every y 2 Y, there is some x 2 X such that F(x) = y.
bijective, or a one-to-one correspondence, if it is both injective and surjective.
But i find it hard to determine wether a function is onto or one-to-one, so can someone please help me.