But the trench curved. Up ahead, a massive blast door was sliding shut. Three turrets in a row fired simultaneously:

He sighed, typed x = 12 , and hit Enter.

The equation appeared on Leo’s screen:

[ x = 3 \quad \textor \quad x = -13 ]

Leo remembered the trench run’s secret: Context. The door opened with positive velocity. The core’s energy signature was positive. He chose: