Classify each function as injective, surjective, bijective, ornone of these.
a) f1 : N --> Q defined by f1 (n) =n/(n+1)
b) f2: Z --> Z defined by f2(n) =n2
c) f3 : N --> N defined by f3(n) =n3
d) f4 : B --> (0, infinity) defined byf4 (C) = the area of C, where B is the set of allcircles in the firs quadrant that are simultaneously tangent toboth the positive x and y axes.
e) f5: A --> (0, infinity) defined byf5(R) = the area of R, where A is the set of all"not-taller-than-wide" rectangles in the first quadrant with on eangle at the origin (i.e., the one side lying along the positivex-axis and another side lying along the positive y-axis, and thewidth of any rectangle in A is greater than or equal to itsheight).
