Final answer:
The function f is neither injective because it maps two elements of X to the same element of Y, nor surjective because not all elements of Y are covered.
Step-by-step explanation:
The function f maps set X to set Y, where X = (1,5,9) and Y = (3,4,7), and is defined as f(1) = 4, f(5) = 7, f(9) = 4. To determine if f is injective (or one-to-one), each element of X must map to a unique element of Y. Since f(1) and f(9) both map to 4, the function is not injective. To determine if f is surjective (or onto), every element of Y must be the image of some element of X under f. Since no element in X maps to 3 in Y, the function is not surjective.