Tell wether the relation is a function (4,5), (-3,2), (4,9), (-2,-3)

Answer 1

No. the points (4,5) and (4,9) have two different y-values for the given x-value (4). this fails the vertical line test.

Answer 2

at x=4, doesn't y have more than one value? Is that allowed in a function?

Answer 3

blake i understand what u are saying i just don't understand ur explanation

Answer 4

try drawing a graph. in the definition of a function, an x value can only have one y value. since the x value of four has two y values (5 and 9), it can't be a function.

try going to wikipedia and searching for "function mathematics" if you're still having trouble. it has the definition and explains it with examples.