Which of the following choices below represents a function? 1. y^2 = 8x - 7
2. y = x/6 + 13
3. y = x^2 - 5

Please help!
(^2 means squared btw)

Which of the binomials below is a factor of this trinominal? x^2-13+30

Jackie purchased 3 bottles of water and 2 cups of coffee for a family for $7.35. brian bought 4 bottles of water and 1 cup of coffee for his family for $7.15. how much does each bottle of water cost? how much does each cup of coffee cost? i need this done

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?