It says one is only 16, how is it can you explain and show

2) For every value of a there is only one value of y. In other words, you can't have two buildings on the same spot. This means y = x2 is a function, but y = vx is not. Why? Let's find the value of x2 and va at a = 4. For the function y = y = 16 at x = 4. However, for y = vx, y can be either +2 or -2 at x = 4 At x = 4 there are two possible values of y for the function y = Va, but only one value for y for the function y = x2. In other words, Va is ambiguous between two possible numbers, and x2 is not. That's why a is a function and va is not. Pictorially, this is a function: 100 f (x ) = x2 This is a function because for every value of x there is only ONE 60 value of y. 40