Question

+1 medal and +1 fan if you help!!!

Which of the following expressions represents a function?

A: y=x^2
B: {(9,2), (4,-2), (5,3), (9,-4)}
C: x=-3
D: x^2=25-y^2

Answer 1

which one passes the vertical line test?

Answer 2

a parabola
points on a plane
a vertical line
or a circle??

Answer 3

A function has ordered pairs where x - elements have only ONE y - element

Answer 4

The second option has x = 9, where it gives two different y values so it's not a function

Answer 5

Use a vertical line test @The_Yee_Dinosaur if the line goes through every point only once then it is a function otherwise it's not

Answer 6

So a circle would not be a function, if you do the vertical line test the following would happen see how the lines are going through two points, we can conclude it's not a function.

Answer 7

Anyways, x = -3 is a vertical line so that is not a function, as it's go through more than one point.

Answer 8

That leaves us with only one option being a function.

Answer 9

so @Astrophysics your saying that the answer is A: y=x^2? Because that was my first guess.

Answer 10

Yup :)