Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

You are not logged in.

## #1 Re: Help Me ! » proof question. » 2006-04-24 04:18:16

Still having promblem with the proof questions! I would be greatly if someone can help

Kind Regards,

dadon

## #2 Re: Help Me ! » proof question. » 2006-04-22 07:17:27

lol stole my thread!

## #3 Help Me ! » proof question. » 2006-04-21 02:32:29

dadon
Replies: 4

Hey guys,

Needed some help on 2 proof questions:

1) Prove that the centre of mass of a uniform wire in the form of a semi-circle of radius r is at a distance 2r/pie (sorry don't know how to insert symbol) from the centre.

2) Prove that the centre of mass of a uniform semi-circular laminar of radius r is at a distance 4r/3pie from the centre.

I hope you guys can help. Thanks

kind regards,

dadon

## #4 Re: Help Me ! » equ. of line and gradient qus. » 2006-04-16 22:59:18

Looking back I made some typing mistakes! in 1) and 5)

1) equation should be 4x - 2y - 5 = 0

5) If the 'equation' of a curve is y=2x^2 -3x -2. Find

a) the gradient at the point where x=0
b) the co-ordinates of the point where y=0
c) the gradient at each of the points found in b)

I mainly need help on question 5)

As I went over this topic last night and can do most of them now.

Regards,

dadon

## #5 Re: Help Me ! » equ. of line and gradient qus. » 2006-04-16 22:52:11

lol sorry for about this! i just wanted some1 to attempt one of the question so I can have some idea what you do. I know it just seem rude for me to post a whole bunch of qus. So im sorry about that.

and btw this is not home-work just going through past papers and picking the questions I cannot do. As you can see there all about gradients and finding the co-ordinates.

regards,

dadon

## #6 Re: Help Me ! » circle » 2006-04-16 22:43:20

Hey thanks I can see what you have done. I wasn't quite sure what it meant by the 'positive quadrant'.

Thanks for explaining the process!

Regards

dado

## #7 Help Me ! » equ. of line and gradient qus. » 2006-04-16 08:21:56

dadon
Replies: 4

1) Find the equation of the line through the origin which is parallel to the line 4x - 27 - 5 = 0

------------------------------------------------------

2) The equation of a curve is y = (x-3)(x+4). Find the gradient of the curve:
a) at the point the curve crosses the y-axis
b) at each of the points where the curve crosses the x-axis

------------------------------------------------------

3) Find the coordinates of the point(s) on the curve y=3x^3 - x + 8 at which the gradient is
a) 8
b) 0

------------------------------------------------------

4) The equation of a curve s=4t^2 +5t. Find the gradient of the normal at each of the points where the curve crosses the t-axis.

------------------------------------------------------

5) If the gradient of a curve is y=2x^2 -3x -2. Find
a) the gradient at the point where x=0
b) the co-ordinates of the point where y=0
c) the gradient at each of the points found in b)

## #8 Help Me ! » Derivative » 2006-04-15 08:39:51

dadon
Replies: 1

Need help for the following question

Find the derivative of:

## #9 Re: Help Me ! » Rate of change » 2006-04-15 01:37:22

Thanks its just the chain rule! cool

At least I don't have to learn anything new!

Regards,

dadon

## #10 Re: Help Me ! » Rate of change » 2006-04-14 23:31:32

Heys thanks I get what you have done!

Could you explain the composite rule as I havn't come across that.

Thanks agian!:)

## #11 Help Me ! » circle » 2006-04-14 03:20:08

dadon
Replies: 2

I have done part a) of the question which need checking & need help on part b)

a) Find the centre and radius of the following circle:

2x^2 + 2y^2 + -4x + 10y = 8

radius = 3.3 centre = (1, -2.5) << this is what i got

b) Find the equation of the tangent to the circle when the circle intersects the x-axis in the positive quadrant.

## #12 Help Me ! » Rate of change » 2006-04-13 06:18:36

dadon
Replies: 4

How do you do the following rate of change questions

when t = 1.2 for all the following questions:

1) y = 4/t + 4lnt

2) x = sin(t^2 +1)  ,  y = cos(2t -3)

3) x = 1 / 1+2t  ,  y = t / 1+t

4) q = 2e^-t/2.cos2t       (e is exponential for this question)

5) x = e^2t.t^3(2-t)^4   (e is exponential for this question)

If someone could help I would be very greatful!

Thanks

## #13 Re: Help Me ! » Rational equation & Rearranging formula » 2006-04-12 23:20:30

thank you exactly what i needed!

## #14 Help Me ! » Rational equation & Rearranging formula » 2006-04-12 22:35:49

dadon
Replies: 3

i needed some help

how do you so the following rational equation

(x-1)^2 / x-2 = 9 / 2

and also

how do you make y the subject of the formula when

y+2 / y+1 = x

i been trying to solve this all morning!

anyways guys if you can help please

## Board footer

Powered by FluxBB