Can you show that x2y24 is not a function without using the

Can you show that x^2-y^2=4 is not a function without using the vertical line test .

Solution

x²-y²=4

We can check it by plugging different values of x and find out the corresponding value of y.

And if on plugging we get values such that the x coordinates are different but the y values are same,then it is not a function

When x=2,y=0 and when x=-2 y=0

Therefore at different values of x, we are getting same value for y.

Hence x²-y²=4 is not a function