Question

which of this equations represent a function
A.y=3x
B.y^2=x^2
C.x^2+y^2=1
D.y=x^2

Answer 1

which one do you think would pass the "vertical line test"?

Answer 2

i know one of them has to be A,D?

Answer 3

ok, so you're ruling out B and C then
well, you're correct, B and C are both ellipses and won't pass the vertical line test

so do you think D would pass it?

Answer 4

well i think it wouldnt because its y=x^2

Answer 5

C is a circle.
B is very interesting looking. You should graph it.

Answer 6

B is an ellipse

Answer 7

well, let's graph it
x = 0, y = 0
x = 2, y = 4
x = -2, y = 4

Answer 8

There is no ellipse in this problem.

Answer 9

well, low and behold! it passes the vertical line test BUT
2 different "x" have the same "y" value, and in a function, that's a no go
so isn't a function either, that leaves you only with "A"

Answer 10

yeah

Answer 11

thanks

Answer 12

yw

Answer 13

The answer is A and D.

B is a pair of intersecting lines, so it's not a function.
C is a circle, so it's not a function.

A is a cubic polynomial and is a function.
D is a parabola that opens up and is a function.

Answer 14

i know the guy was trolling me

Answer 15

@jdoe0001
You were on the right track but got lost along the way.
Any function that passes the vertical line test is a function. There is no exception to this rule.

A function cannot have the same x-coordinate used twice, but a function can have the same y-coordinate used with many different x-coordinates.