f(x,y,z) =x^2+3xy-z^2+2y+z+4 at P(o,0,0) ; v= i+j+k.
a. What is the direction in which f increases most rapidly? give ans in (a/sqrtb)j + (c/sqrtd)k
b. What is the direction in which f decreases most rapidly? Ans as (a/sqrtb)j + (c/sqrtd) k
c. What is the derivative of f in the direction of the vector v?