Question

Which of the following relations is a function?
a) {(2,6), (3,9), (4,2), (3,6)}
b){(2,8), (3,6), (2,4), (0,2)}
c){(3,-2), (4,7), (-2,5), (-4,5)}
d) {(4,7), (-2,5), (1,3), (-2,1)}

Answer 1

for a function we can't have the left the x repeat.

Answer 2

{(2,6), (3,9), (4,2), (3,6)} - no has a repeating 3
{(2,8), (3,6), (2,4), (0,2)} - no has a repeating 2
{(3,-2), (4,7), (-2,5), (-4,5)} - yes
{(4,7), (-2,5), (1,3), (-2,1)} - no has a repeating -2

Answer 3

So That Means...? It would be c, due to nothing repeating?

Answer 4

yeah....

Answer 5

If you have a graph instead of a table, at no spot on the graph can a vertical line pass through the graph twice.

Answer 6

Same idea: only 1 value of y for each value of x.

Answer 7

I just look at (x,y) and if any x value repeats... can't be a function

Answer 8

Thank you. :)

Answer 9

but yes we can do a vertical line test as well. if it passes through something twice, not a function... example.. draw a circle..now draw a vertical line

Answer 10

You do have to be a little more careful: if both x and y repeat, it may be a function!

\[(2,8), (3,6), (2,8), (0,2)\]

is a function. While \(x=2\) repeats, you have the same value of \(y\) for both of them.

Answer 11

one-to - one function is the horizontal line test