Ineed . its very emergency

the group of points {(0, 1), (0, 5), (2, 6), (3, 3)} is not a function, but the group of points {(1, 4), (2, 7), (3, 1), (5, 7)} is a function. what do you notice about the two groups of points? what do you think it means to be a function?

ps and again i really need the answers.

Here it is:

The first set has (0,1) and (0,5), which assigns to the *same* x, more than one value of *y*. That's not a function. It's a curve. Think about a circle, or instance. It's NOT a function, but it's a curve.

The second one has for each *x* a single *y*

BTW, there's no problem if for *different* x there is the same *y*:

y = 5,

all x, have the same y, equal to 5. That's a function, or y = x^2, etc

The definition of a function is that for every unique input, independent variable, there is only one unique output, dependent variable.  Otherwise is fails what is called the "vertical line test" which just means that there can only be one specific output value for any one specific input value.

Your cleary not see the answer is 25