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## gary's Content

There have been 535 items by gary (Search limited from 07-August 21)

### #9200 Struggling

Posted by gary on 12 November 2004 - 05:15 PM in Mathematics

6/6

5/8

15/16

3/4

So I was very happy.

### #9202 Most demanding subject

Posted by gary on 12 November 2004 - 05:24 PM in General Chat

This year probably Higher Chemistry.

### #9255 Differentiation

Posted by gary on 13 November 2004 - 10:52 PM in Mathematics

In the diagram the rectangle ABCD represents the outside of the case which measures 40 cm by 30 cm. The triangle within the rectangle represents the blue plastic triangle which is placed so that the lengths of the lines AE and DF are x centimetres and 2x centimetres respectively.

A show that the area S square centimetres of the triangle CEF is given by s(x) = 600 - 30x x x2

(b) Show the interval of values of x on which the function s(x) is defined.

© use calculus to find the greatest and least possible values for the area of triangle cef.

peakland plastics manufacture food containers which have a square base and are cuboid in shape. The sides and base are made of rigid plastic and the lid is made of flexible plastic. the company decide to add a new size of container to this range. it is to have a volume of 4000 cubic centimetres.

(a) if x centimetres is the length of each edge of the base of this container. show that the total area h centimetres of the rigid plastic used is given by

h = x2 + 16000/x

(b) find the dimensions of the container which ensure that the minimum possible area of rigid plastic is used.

### #9265 Differentiation

Posted by gary on 14 November 2004 - 03:18 PM in Mathematics

x3 = 8000

x = 20

How do you get 20 from that?

### #9369 Most demanding subject

Posted by gary on 16 November 2004 - 07:27 PM in General Chat

### #9401 Gmail

Posted by gary on 16 November 2004 - 11:02 PM in General Chat

### #9861 Ucas Forms

Posted by gary on 23 November 2004 - 07:18 PM in Course Choices

### #9867 Ucas Forms

Posted by gary on 23 November 2004 - 07:49 PM in Course Choices

### #10578 Help With Questions

Posted by gary on 04 December 2004 - 10:46 AM in Chemistry

A It can decolourise bromine water

B All of the c-c bond lengths are equal

C It does not really undergo addition reactions

D The electrons in benzene are delocalised

When ethylbenzene is converted to phenylethene what is the reaction called?

A Reduction

B Dehydrogenation

C Dehydration

D Polymerisation

E Reforming

A compound C7 H12 02 reacts with sodium carbonate solution liberating carbon dioxide gas, and it also decolourises bromine water rapidly. What would be its structural formula.

The next two questions might be hard to understand as they are one of the grid questions.

How is and alcohol H-C-C-O-H produced from CH2 double bond CH2?

How would you convert and alcohol H-C-C-O-H into an addition bromine reaction (2 steps required)

Thanks for any help.

### #10580 Quadratics Questions

Posted by gary on 04 December 2004 - 10:54 AM in Mathematics

Rewrite R in the form a(x-p)2 + q by completing the square. stating the values of a,p and q clearly.

Hence state the maximum value of R and the corresponding value of x.

Complete the square on the expressions -x2 - 4x + 1

Hence show that, for the curve with the equation y= -1/3xcubed - 2xsquared + x -7, the gradient of the tangent cannot be greater than 5.

State the value of x for which the gradient of the tangent equals 5.

Thanks for any help.

### #10581 What do you think you will get in the final exam?

Posted by gary on 04 December 2004 - 10:56 AM in Mathematics

### #10661 Quadratics Questions

Posted by gary on 05 December 2004 - 01:56 PM in Mathematics

### #10678 Quadratics Questions

Posted by gary on 05 December 2004 - 03:16 PM in Mathematics

-x(^2) - 4x + 1.

I'm still confused with the first question this is how I have done it:

-1 ( x(^2) - 50x - 475)

-1 ( (x-25)squared - 475 - 25(^2)

-1 ( (x-25)squared - 475 - 625)

1100 (x-25)squared

Thanks if you help again I'm just confused by the whole quadratic topic.

### #10683 Quadratics Questions

Posted by gary on 05 December 2004 - 03:51 PM in Mathematics

### #11530 Straight Line Geometry Problem

Posted by gary on 21 December 2004 - 07:18 PM in Mathematics

Find the equations of PS and QS

Hence find the oordinates of the fourth vertex S

Thanks for any help.

### #12469 Differentiation Problem

Posted by gary on 22 January 2005 - 01:16 PM in Mathematics

*Find the x-coordinate of each of the points on the curve y= 2x*

^{3}- 3x^{2}- 12x + 20 at which the tangent is parallel to the x-axis.Also if anyone has past papers can you help me with the following:

1993 paper 1 Q8

1993 paper 1 Q10

1993 paper 1 Q 11

### #12471 Getting good grades

Posted by gary on 22 January 2005 - 01:19 PM in Revision and Exams

### #12494 Differentiation Problem

Posted by gary on 22 January 2005 - 02:41 PM in Mathematics

I can do most of these questions it is just trying to figure out tangent problems and what topic they are related to.

I would post the 1993 questions but they all involve graphs so it is too difficult to explain.

### #12499 Differentiation Problem

Posted by gary on 22 January 2005 - 05:53 PM in Mathematics

I will go over them now to see if I can understand them.

### #12501 Differentiation Problem

Posted by gary on 22 January 2005 - 05:58 PM in Mathematics

### #12502 Differentiation Problem

Posted by gary on 22 January 2005 - 06:04 PM in Mathematics

### #12709 stress for exams

Posted by gary on 26 January 2005 - 05:57 PM in Mathematics

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