00:01
In this problem, we have f of x, y, z given as 4 plus sin of 2x plus y minus z.
00:13
We are given b as minus pi by 6, pi by 6, pi by 6 and we are given unit vector u as minus 1 by 3, minus 2 by 3 and then 2 by 3.
00:32
So, for the first part, to find the gradient of f, gradient of f x, y, z is nothing but dou f by dou x i cap plus dou f by dou y j cap plus dou f by dou z.
00:53
So, this is nothing but dou f by dou x, this is nothing but 2 times cos of 2x plus y minus z i cap plus, this is simply cos of 2x plus y minus z j cap and dou f by dou z is minus cos of 2x plus y minus z.
01:22
Now, to find the gradient at p, we have x as minus pi by 6, y as pi by 6 and z as pi by 6.
01:36
So, this becomes 2x is minus 2 pi by 6, pi by 6 is minus pi by 6 and then again minus pi by 6.
01:45
So, this is 2 times cos of minus pi by 3 d i cap and we have 2x plus y as minus pi by 6 and then again minus pi by 6, minus pi by 3.
02:06
So, this is plus cos of minus pi by 3 j cap and then we have minus cos of minus pi by 3 j cap.
02:18
So, continuing we have this at minus pi by 6, pi by 6, pi by 6 simply becomes substituting cos of minus pi by 3 same as cos of pi by 3, which is 1 by 2.
02:33
So, this is simply i cap, this is plus 1 by 2 j cap and this is minus 1 by 2 k cap.
02:44
Next we have to find the unit vector in the direction of maximum increase...