In this project I will be using 2 methods to find the gradients of curves with the formula: y=axn

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Introduction

In this project I will be using 2 methods to find the gradients of curves with the formula:

y=axn

The two methods I will be using are the tangent method and the small increase method.

The tangent method involves drawing a line, by hand, which reflects the gradient.

The graph shown above is the curve y=x2. The line drawn on the graph is the gradient at the point (3,9). The Gradient is worked out by using this formula:

QN

MN

In this example the gradient is:

9

1.5

= 6

This method is inaccurate because it is drawn by eye and no real mathematics was involved to find the gradient.


The small increase method is a more precise method of finding the gradient of a curve. It uses 2 points on the same curve, which are very close to each other, and uses the straight line between the points as the tangent. As this increase becomes gradually smaller, the line reflects the gradient more and more.
Graph → y=3x3

Small increase method

Fixed point A (1,3)

B1 = (1.1,3.993)

B2 = (1.01,3.090903)

B3 = (1.01,3.009009003)

AB1 Gradient        =        3.993-3

                        1.1-1

                =        0.993

                        0.1

                =        9.93

AB2 Gradient        =        3.090903-3

                        1.01-1

                =        0.090903

                        0.01

                =        9.0903

AB3 Gradient        =        3.009009003-3

                        0.001

                =        0.009009003

                        0.001

                =        9.009003

The Gradient is approaching 9

                         


Graph → y=3x3

Small increase method

Fixed point A= (2,24)

B1= (2.01,24.361803)

B2= (2.001,24.036018)

B3= (2.0001,24.00360018)

AB1 Gradient        =        24.361803-24

                        2.01-2

                =        0.361803

                        0.01

                =        36.1803

AB2 Gradient        =        24.036018-24

                        2.001-2

                =        0.036018

                        0.001

                =        36.018

AB3 Gradient        =        24.00360018-24

                        2.0001-2

                =        0.00360018

                        0.0001

                =        36.0018

The Gradient is approaching 36


Graph → y=3x3

Small increase method

Fixed point A= (3,81)

B1= (3.01,81.812703)

B2= (3.001,81.081027)

B3= (2.0001,81.00810027)

AB1 Gradient        =         81.812703-81

                        3.01-3

                =        0.812703

                        0.01

                =        81.2703

AB2 Gradient        =        81.081027-81

                        3.001-3

                =        0.081027

                        0.001

                =        81.027003

AB3 Gradient        =        81.00810027-81

Join now!

                        3.0001-3

                =        0.00810027

                        0.0001

                =        81.00270003

The gradient is approaching 81


Tabulating The Results For Graph → y=3x3

The formula for this graph is:

Gradient= 9(x2)


Graph → y=x3

Drawing tangents

Point x= (1,1)

Point y= (2,8)

Point z= (3,27)

Triangle A (point x)=         2

                                0.5

Triangle B (point y)=         6.5

                                0.5

Triangle C (point z)=        14

                                0.5

Gradient x= 4

Gradient y= 13

Gradient z= 28


Graph → y=x3

Small increase method

Fixed point A= (1,1)

B1= (1.1,1.13)

B2= ...

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