Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**EMPhillips1989****Member**- Registered: 2008-01-21
- Posts: 40

let

i've found the gradient of f as

i now need to find the unit normal to the surface

at the point (2,-2,2)does anyone know a formula i can use to find this? please help!

*Last edited by EMPhillips1989 (2008-03-11 00:39:22)*

Offline

**luca-deltodesco****Member**- Registered: 2006-05-05
- Posts: 1,470

the gradient normalised IS the normal, substitute the values of x,y,z into the gradient function, and normalise the vector.

also, you should have -2xk not +2xk

*Last edited by luca-deltodesco (2008-03-10 23:58:14)*

The Beginning Of All Things To End.

The End Of All Things To Come.

Offline

**EMPhillips1989****Member**- Registered: 2008-01-21
- Posts: 40

So is this correct?

Offline

**luca-deltodesco****Member**- Registered: 2006-05-05
- Posts: 1,470

yeh, thats fine, but then you have to normalise it for the unit normal

so:

The Beginning Of All Things To End.

The End Of All Things To Come.

Offline

**Ricky****Moderator**- Registered: 2005-12-04
- Posts: 3,791

If my memory serves me right, this is the proper symbol for gradient:

"In the real world, this would be a problem. But in mathematics, we can just define a place where this problem doesn't exist. So we'll go ahead and do that now..."

Offline

**Monox D. I-Fly****Member**- Registered: 2015-12-02
- Posts: 730

Ricky wrote:

If my memory serves me right, this is the proper symbol for gradient:

I... never knew that despite I am a math graduate and often spend my time in math forums. In my country, gradient is generally symbolized as m.

Offline

Ricky wrote:

Indeed, though is my preference. typically denotes the Laplace operator.
If my memory serves me right, this is the proper symbol for gradient:

**LearnMathsFree: Videos on various topics.New: Integration Problem | Adding FractionsPopular: Continued Fractions | Metric Spaces | Duality**

Offline