Question

x^2+y^2= 4 Correct me if I'm wrong but I got y = +- sqrt of 4-x^2 . The question is to determine whether the equation represents y as a function of X. The book says it's not a function. Why is that? please explain

Answer 1

they didn't ask you to solve for y. they asked if it was y as a function of x. which it isn't until you do what you did.

Answer 2

It represents a circle. and for one x value, there are two y values

Answer 3

In the examples for it , it says solve for Y in terms of X to deter mine?

Answer 4

that is because you have the +-. doesn't pass the vertical line test, hence, not a function. plug in x = 1 and you will get square root of 3 and negative square root of 3. two y's for each x except @ x=2, so not a function.

Answer 5

what radar said. i is a circle with center at the origin and radius 2, so doesn't pass vertical line test

Answer 6

hhaha I just read that in the book!
Thank you so much guys! I got it now! :)

Answer 7

also note that both (0,2) and (0,-2) are on the graph so one input gives to outputs
so not a function