Respuesta :
It is true because each input has only 1 output.
in other words, each x value has a separate y value. An x value doesn't come twice and have a different y value each time. If it did, it wouldn't be a function.
in other words, each x value has a separate y value. An x value doesn't come twice and have a different y value each time. If it did, it wouldn't be a function.