Is my answer correct?
Directions: Determine whether y is a function of x.
Problem: x^2+y^2=16
Answer:
x^2+y^2+-x^2=16+-x^2
y^2=-x^2+16
y= ±√-x^2+16
y is not a function of x
y^2 = 16 - x^2
y = +/- sqrt(16-x^2)
There must be one and ONLY ONE
value of y for every value of x
However we have TWO
So you are right, y is not a function of x
In fact this is a circle with center at the origin and radius 4
The domain is x = -4 to x = +4
The range is y = -4 to + 4
and there are two values of y for each value of x inside the domain