Find the directions in which the function increases and decreases most rapidly at Po. Then find the derivatives of the function in these directions. f(x,y,z) = (x/y) -yz, Po(- 4, - 1, - 1) The direction in which the given function f(x,y,z) =(x/y) -yz increases most rapidly at Po ( -4, -1, -1) is u -|i+() +k. (Type exact answers, using radicals as needed.) The direction in which the given function f(x,y,z) = (x/y) -yz decreases most rapidly at Po ( - 4, - 1, - 1) is v = (Type exact answers, using radicals as needed.) The derivative of the given function f(x,y,z) =(x/y) -yz in the direction in which the function increases most rapidly at Po( - 4, - 1, - 1) is Duf= (Type an exact answer, using radicals as needed.) The derivative of the given function f(x,y,z) = (x/y) -yz in the direction in which the function decreases most rapidly at Po( - 4, - 1, - 1) is Dyf= (Type an exact answer, using radicals as needed.)