Summary: Math 213-001 201130
Assignment # 5 - Sample answers
1. Find the gradient of f, evaluate the gradient at the point P, and find
the rate of change of f at P in the direction of the vector u.
(a) f(x, y) = y ln x, P = (1, -3), u =
5
13
i +
12
13
.
Answer.
f(x, y) =
y
x
i + ln(x),
so
f(1, -3) = -3i.
u is already a unit vector so we calculate
Duf(1, -3) = u · f(1, -3) = (

Source: Argerami, Martin - Department of Mathematics and Statistics, University of Regina

Collections: Mathematics