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(- 1, - 1, -4) The direction in which the given function f(x,y,z) = (x/y) - yz increases most rapidly at Po( - 1, - 1, -4) is u = i+ (Di+ ())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( - 1, - 1, -4) is - u = i+ (Ji+ (])k. (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( - 1, - 1, - 4) is (Duf) (-1, -1,-4) =- (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( - 1, - 1, -4) is (D-uf) (=1, -1, -4) = (Type an exact answer, using radicals as needed.)