At an orbital research station, Emek and Tara learned that a satellite had drifted from its planned path. The navigation system could transmit a correction signal only when the satellite's alignment value reached zero. For the next several hours, the system modeled that value with the polynomial t^2 - 7t - 18, where t represented hours from the present. Emek factored the polynomial as (t - 9)(t + 2). Setting each factor equal to zero gave two possible times: t = 9 and t = -2. Tara explained that t = -2 represented an alignment that had occurred two hours earlier, so it could no longer be used. The solution t = 9 represented the next usable alignment, nine hours in the future. They checked their result by substituting 9 into the original polynomial and obtaining 0. Emek programmed the system to transmit at that time. Nine hours later, the signal reached the satellite during the predicted alignment, and its guidance system successfully returned it to the intended orbit.