MATH1901 help (1 Viewer)

[withoutaface]

Can someone help me on 2003 question 5?

http://www.library.usyd.edu.au/exams/exam03/038015.pdf

 

[xiao1985]

lol hafn't done this in a long shot, but grad (f) should be the vector which is perpendicular to tgt surface, and part b, just dot grad f with (x - xo)

 

[Xayma]

Justin:

http://www.math.columbia.edu/~tsui/3asp05/homework/hw7_sol.pdf

It goes through the working for one example.

It involves grad of three variables so not 100% sure if it was removed from the syllabus or not.

 

[acmilan]

I dont think its in the course but you have to use 3d vector (sorry if your link explains this Xayma because i didnt check it out )

Didnt try the first part but i think you use:

grad = f_x(x,y)i + f_y(x,y)j + f_z(x,y)k

For the second part, use the tangent's equation and you'll get the answer:

f_x(x₀,y₀,z₀)(x - x₀) + f_y(x₀,y₀,z₀)(y - y₀) + f_z(x₀,y₀,z₀)(z - z₀) = 0

 

[gordo]

can we get answers to past exam papers?

 

[evilc]

I think for the first part you use the equation:

r (x,y,z) = p + tgradF(p)

r = (x0,y0,z0) + t (2x0/a², 2y0/b²,2z0/c²)

I'm not totally sure though. I hated this stuff when i did it last year.

 

[Xayma]

I dont think its in the course but you have to use 3d vector (sorry if your link explains this Xayma because i didnt check it out )

Didnt try the first part but i think you use:

grad = f_x(x,y)i + f_y(x,y)j + f_z(x,y)k

For the second part, use the tangent's equation and you'll get the answer:

f_x(x₀,y₀,z₀)(x - x₀) + f_y(x₀,y₀,z₀)(y - y₀) + f_z(x₀,y₀,z₀)(z - z₀) = 0

That's exactly it vince except it is actually f_x(x,y,z) etc How you have f_z(x,y) is beyond me