Ответ:

(7m - 3u) • (7a - 9m)

Объяснение:

49am+27mu−21au−63m^2 =

(49 am - 21 au) + (27 mu - 63 m^2) = 7a (7m - 3u) + 9m (3u - 7m) = 7a (7m - 3u) - 9m (7 m - 3 u) = (7m - 3u) • (7a - 9m)