Find the directional derivative of:
∅=(x+2y+z)²—(x—y—z)² at the point (2, 1, -1) in the direction of A=i—4j+2k.
Plz help show me work
∅=(x+2y+z)²—(x—y—z)² at the point (2, 1, -1) in the direction of A=i—4j+2k.
Plz help show me work