he found a single value for x that maps to two values of y, so it is not a function, since both y's work for 1 x
the first one is not a function at all, the second is a 1-1 function
Are these one-to-one functions?
through inspection. he realized that the y is squared, so for any positive y-value we plug in, we will get the same answer as when we plug in the negative of that value
Where did you get those values in terms of (x,y)?