Math Is Fun Forum

Marisca

Member

Registered: 2011-04-22

Posts: 53

Differentiation help needed!

Hi, I'm having trouble with this question.

For a curve with equation y=x^2+5x
a) find the gradient of the chord PQ where P is the point (2.14) and Q is the point (2+h,(2+h)^2+5(2+h)).

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Differentiation help needed!

Hi Marisca;

Isn't the gradient in this case the same as the slope?

I am getting a gradient of m = 9 + h.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,196

Re: Differentiation help needed!

hi Marisca,

Like this:

If you let h tend to zero this gives 9.  This is what you'd get if you differentiate and put x = 2.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Marisca

Member

Registered: 2011-04-22

Posts: 53

Re: Differentiation help needed!

Ah! I get it now. Thanks, I didn't realize that (2+h,(2+h)^2+5(2+h)) was a coordinate.

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Differentiation help needed!

hi Marisca

If you want,check out this:http://mathisfunforum.com/viewtopic.php?id=17656

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