i don't understand how the square root of 4 can be both 2 and -2 can you please explain btw i need an answer asap

2) For every value of r there is only one value of y. In other words, you can't have two buildings on the same spot. Thi means y -r is a function, but y r is not. Why? Let's find the value of r and vr at r - 4. For the function y- y 16atr -,However, for y = vr, y can be either +2 or -2 at 1- At I - 4 there are two possible values of y for the function y = vz, but only one value for y for the function y = r . In other words, va is ambiguous between two possible numbers, and r2 is not. That's why I is a function and vr is not. Pictorially, this is a function