The correct equation that shows the relation between the vertices of a dilated figure and the vertices of the original figure when the original figure is dilated using a scale factor of 5 is:
\[ (x_2, y_2) = (5x_1, 5y_1) \]
This indicates that each coordinate of the vertices of the original figure (denoted as \( (x_1, y_1) \)) is multiplied by the scale factor (5 in this case) to obtain the coordinates of the vertices of the dilated figure (denoted as \( (x_2, y_2) \)).