• Jun 4th 2006, 08:51 AM
Susan111
Hi!

How many methods are there of finding the gradient of a point on a curve? And can someone pleeeease explain them to me, I tried looking at books and the internet, but it's just all so confusing, I don't understand a word of it! This is for an extension thing at school, so I don't know any thing about calculus... :(

Help would be appreciated!

Suzanna :D
• Jun 4th 2006, 09:20 AM
malaygoel
Quote:

Originally Posted by Susan111
Hi!

How many methods are there of finding the gradient of a point on a curve? Suzanna :D

there are no methods for finding the gradient of a point on a curve but methods are there for finding the gradient of a curve at a point.
One of the methods which I know is finding dy/dx when curve is defined in terms of x and y.
There are many methods for finding dy/dx
• Jun 5th 2006, 01:20 AM
earboth
Quote:

Originally Posted by Susan111
Hi!

How many methods are there of finding the gradient of a point on a curve? And can someone pleeeease explain them to me, I tried looking at books and the internet, but it's just all so confusing, I don't understand a word of it! This is for an extension thing at school, so I don't know any thing about calculus... :(
Help would be appreciated!
Suzanna :D

Hello,

I presume that you never have done calculus in school. I further presume that you know to calculate the slope of a line if there are given two points of the line.

The same method is used to calculate the slope of a chord, connecting two points which belong to a graph of a function. (Look at the 1rst attached diagram). If the point A has the coordinates A(x_0, f(x_0)) and B(x_1,f(x_1)) then you get:

$\displaystyle m=\frac{f(x_1))-f(x_0))}{x_1-x_0}$ or more shortly: $\displaystyle m=\frac{\Delta(f)}{\Delta x}$.

Now imagine that the point B approaches the point A. That means that the $\displaystyle \Delta x$ is approaching zero. The slope of the chord is approaching the slope of the tangent in point A at the graph of the function f. The slope of the tangent in A is called the gradient of f in A. (look at the 2nd attached diagram)

What I've described (roughly!) in words you can calculate:

$\displaystyle \lim_{\csub{\Delta x \to 0}}{\frac{\Delta(f)}{\Delta x}}=\frac{d(f)}{dx}=f'(x)$.

This quotient is called the 1rst derivative of f. It is a function which gives the value of the gradient for every value of x.

I don't know if you asked for this explanation. If so, I hope this is of some help for you.

Greetings

EB
• Jun 5th 2006, 08:47 AM
Susan111
Thanks so much for your help! :D