why

>>33028
You need to be 18 years old or older to browse this site.

>>33028
dude, y as a function of x...

obviously the circle in question one has neither being a function independent of the other, but when something is a function of something else then one has to be dependent and the other not.

question 2 is in the form of x as a function of y, not the other way around. Either you are confused or you dont get what functions are. prepare your anus when you get to calc and especially multivariant calc

>>33029
while i suspect anon is underage B&, this could easily be remedial algebra.

>>33030
No, question 2 IS representative of y as a function of x.
When y is a function of x, then y is alone on one side of the equation, while x interacts with numbers on the other side. This makes it so that y, having nothing else acting upon it, is ultimately dependent on x, and therefore a function of it.

http://ccnmtl.columbia.edu/projects/mmt/frontiers/web/chapter_3/9121.html

>>33030
But you can solve both graphically.

To input the first into a calculator, you have to put it in the form of the second. They both give the same graph, allowing the use of the vertical line test, demonstrating that both are functions.

File: graph-sqrt.gif (7KB, 770x290px) Image search: [Google]

7KB, 770x290px

>>33028
The problem is probably that while y^2 = a
can have two real solutions,
y = +sqrt(a) and y = - sqrt(a),
when you write y = sqrt(a), sqrt is a function that gives you only the nonnegative solution.

This means that y = sqrt(16 - x^2) is an equation that represents y as a function of x.

>>33028
K i figured it out. The second equation is not the first equation, because square rooting the first equation results in both the positive and negative square root, whereas the second is explicitly only the positive (aka principle) square root.