Question

Show that the elements in sets X and Y define a function f from set X to set Y.

Answer 1

Functions have to pass the vertical line test
this means that each X value should only have one Y value
Here is a link to someone else explaining with pretty drawings: http://www.coolmath.com/algebra/15-functions/04-functions-with-sets-01 (because I can't draw lol)

basically: There can only be one line extending from each X to Y, but there can be more than one line reaching any Y

does this make sense? or would you like for me to make pictures? :)

Answer 2

it makes sense.. @Angle
how do we show the working for this type of question?
must we write in ordered pairs from or..

Answer 3

yes, you can show work by writing out all the ordered pairs and showing that no X value is repeated in any other ordered pair :)

Answer 4

Thank you! @Angle ^_^