Question

A {(2,1),(4, 1), (6, 1), (8, 1)} 4) Choose the set that is a function. B) {(2,1),(4,3), (6,5), (2,7)} {(2, 1), (4, 1), (2, 5), (4,7)} D) {(2, 1), (2, 3), (2, 5), (2,7)}

Answer 1

we know that

A function is a binary relation over two sets that associates every element of the first set, to exactly one element of the second set

so

For one value of x there is only one value of y

Verify each options

Option A

The option A is a function

Option B

Is not a function , because we have the points (2,1) and (2,7)

one value of x and there are two values of y

Option C

Is not a function , because we have

(2,1) and (2,5) -----> one value of x and to values of y

(4,1) and (4,7) --> one value of x and to values of y

Option D

Is not a function ------> one value of x and 4 values of y

therefore

the answer is the option A