Question

The table shows the outputs y, for different inputs ,x

Input x: 3,7,11,15
Output y: 4,6,8,10

Part A: Do the data in this table represent a function? Justify your answer.

Part B: Compare the data in the table with the relation f(x) = 5x-21. Which relation has a greater value when x=11

Part C: Using the relation in part b, what is the value of x if f(x) =99

Answer 1

Part A: Yes, the data represent a function. The definition of a function is a relation in which no value of x will have two different values of y.

(Every time you plug in 3 as x, you will always get 4 as y; it's ok if you plug in 3 and 5 as x and get the same y, you just can't get two different y's for one x; sorry, it is pretty confusing). None of the numbers in the table repeat, so we can safely say that the relation is a function.

Part B: All we have to do is plug in 11 for x in the function given to find the answer:

In the table, y = 8 when x = 11, but in the function given, y = 34 when x = 11, so the function given is greater.

Part C: To find the answer to C, just plug in 99 for f(x), as it tells you to do: