Tetanus bacillus bacterium is cultured to produce tetanus toxin used in an inactive form for the tetanus vaccine. the amount of toxin produced per batch increases with time and then becomes unstable. the amount of toxin (in grams) as a function of time t (in hours) can be approximated by: b(t) = - 1/1426 t^2 + 1/31 t how many hours will it take to produce the maximum yield? the maximum yield will occur in hours.