how far is the electron from the origin when it momentarily stops?

how far is the electron from the origin when it momentarily stops?
An electron moving along the x-axis has a position given by x = Ate – Bt m, where t is in seconds and A and B are positive constants. In terms of A and B, how far is the electron from the origin when it momentarily stops?

how far is the electron from the origin when it momentarily stops?