Need all 3 questions

For each of the following functions, determine if they are a injection, surjection, or bijection. Explain why. 1. f1:QQ,f(x)=3x+2 2. f2:NN,f(x)=3x+2 3. f3:NNN,f(x,y)=5x+3y 4. f4:ZZZ,f(x,y)=5x+3y Exercise 3.6 Consider the function f:Q+Q+such that f(x)=x1. Prove that f is a bijection. Recall that Q+={aQa>0} Exercise 3.7 A grocery store sells hot dogs weiners in packs of 8 and hot dog buns in packs of 12 . If you would like to serve N hot dogs at your next BBQ, what is the minimum number of packages of weiners and buns you must buy for: 1. N=14 2. N=200 3. N=426 In each case, if there are any leftovers, how many leftovers of each ingredient will there be