Discrete Mathe,i need a complete solution.

1. Bijection [10pt]. Let f : {2, 3, 4, . .. } {2, 3, 4, } such that 72 3()'-() Is f is bijective? Prove or disprove. 2. Set Cardinality [10pt]. Let f be the function as defined in question 1 Consider the set Is S a countably infinite set? Prove or disprove it. 3. Set Cardinality[10pt]. Let X and Y be two infinite sets such that X C Y. Let f:XX be an injective function. Can we infer frorn that X = Y? Prove or disprove