Question

If the point (x,-1) is on the unit circle what is the value of x

Answer 1

It's just 0, just inputted it in and got it correct.

Answer 2

A unit circle has its center at the origin and has a radius of one. It is modeled by the equation
x² + y² = 1

We are given with (x,-1) .
Solving for x
x² + (-1)² = 1
x = 0