How many solution does the system with augmented matrix 1 2 3 4 A : 0 2 3 1 0 4 6 2 have? 0 None. 0 Exactly one. Q 2 O Infinitely many If f (:12, y) = 3:23;, then the directional derivative of f in the direction of the vector 11 = (1, 1) at the point (1, 2) is