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#1 2007-06-10 19:09:59

Mel
Guest

Differentiation- gradients

So i know this
y = 5 - x
y'= 5

Then i have to find the gradient at the point (2,3)

Help please?

#2 2007-06-10 19:54:54

yonski
Member
Registered: 2005-12-14
Posts: 67

Re: Differentiation- gradients

I think you're getting a bit confused with the differentiation. To differentiate a linear function like that you need to take the coefficient of x (in this case -1). Remember that the equation for a straight line is y = mx + c , where m is the gradient. When you differentiate you're looking for the sort of 'gradient function', so this should help to remind you.

Once you've done that, the second part of the question is easy. Since it's a straight line graph, the gradient will be the same at every point, i.e. -1.

Hope that helps.


Student: "What's a corollary?"
Lecturer: "What's a corollary? It's like when a theorem has a child. And names it corollary."

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#3 2007-06-11 02:47:27

George,Y
Member
Registered: 2006-03-12
Posts: 1,379

Re: Differentiation- gradients

Acctually the gradient concept is derived from the slope of a line.


X'(y-Xβ)=0

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#4 2007-06-11 06:59:45

yonski
Member
Registered: 2005-12-14
Posts: 67

Re: Differentiation- gradients

I thought that much was obvious.


Student: "What's a corollary?"
Lecturer: "What's a corollary? It's like when a theorem has a child. And names it corollary."

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#5 2007-06-11 20:37:22

Mel
Guest

Re: Differentiation- gradients

hehe u people were wrong.. the answer was 5 not -1

owell

#6 2007-06-11 22:29:10

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: Differentiation- gradients

Well, the answer to what you have written is definitely -1.
Maybe you put a typo in the question?


Why did the vector cross the road?
It wanted to be normal.

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#7 2007-06-11 23:51:19

JaneFairfax
Member
Registered: 2007-02-23
Posts: 6,868

Re: Differentiation- gradients

My hunch is that Mel miswrote the initial equation, which most likely should have been y = 5x−7.

Last edited by JaneFairfax (2007-06-11 23:51:42)

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