Plz help on my maths coursework coz im desperate!

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Vikz13
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#1
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#1
hi ppl....sum1 plzzzzzzz help me coz i gt maths coursework 2 du un i dnt hav a clue hw 2 du it!The sheet i gt given is sumfin 2 du wiv squares that make shapes un the nth term.Its says:
The diadram below shows a dark cross shape that has been surrounded by white squares 2 create a bigger cross.The bigger cross contains 25 squares in total.The next cross shape is always mabe by surrounding the previous cross shape with squares. The next part is the question:
Investigate to see how many squares would be needed to make any cross shape built up in this way.
Im lyk totally stuck un need help can any1 help me plzzzzzzzzzzzzz?!
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#2
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#2
sory can't help u!

but is anyone doin da coureswork where u have 2 find the difference of da products ( number Grid)
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#3
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#3
*** on people!! r we all asleep today!!!!!!!!!!!!!!!!!!!!!
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Jonny W
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The diagram is this, right?

Code:
-
  -*-
 --*--
-*****-
 --*--
  -*-
   -

* = black square
- = white square
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#5
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In these kind of courseworks youre always trying to reach a final equation which will act as a rule. You need to start out by looking at your diagram and counting the number of white and black squares, then make the next size cross and do the same thing. keep on going until youve got quite a lot of data and see if you can find a pattern eg No of white squares = 2(number of black squares) - 4
(thats just made up of course but you get the idea?)

If you can make the rule for a cross with arms of equal length youll be OK but to get high marks you will probably need to go on to look at crosses of different lenghths (like the christian cross) and try and come up with a GENERAL FORMULA for all crosses! Good luck
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jstringer
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(Original post by Vikz13)
hi ppl....sum1 plzzzzzzz help me coz i gt maths coursework 2 du un i dnt hav a clue hw 2 du it!The sheet i gt given is sumfin 2 du wiv squares that make shapes un the nth term.Its says:
The diadram below shows a dark cross shape that has been surrounded by white squares 2 create a bigger cross.The bigger cross contains 25 squares in total.The next cross shape is always mabe by surrounding the previous cross shape with squares. The next part is the question:
Investigate to see how many squares would be needed to make any cross shape built up in this way.
Im lyk totally stuck un need help can any1 help me plzzzzzzzzzzzzz?!
wot you need to do is draw the next few crosses and count the number of squares in each and the work out the pattern.
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Vikz13
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(Original post by Jonny W)
The diagram is this, right?

Code:
-
  -*-
 --*--
-*****-
 --*--
  -*-
   -

* = black square
- = white square

yes dats it can u plzzzz help?????
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Jonny W
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Have a look at these examples:

Code:
Example 1
=========

   -
  -*-
 --*--
-*****-
 --*--
  -*-
   -

B = Number of black squares = 9
W = Number of white squares = 16
 

Example 2
=========

     -
    -*-
    -*-
    -*-
 ----*----
-*********-
 ----*----
    -*-
    -*-
    -*-
     -

B = Number of black squares = 17
W = Number of white squares = 32 


Example 3
=========

     -
    -*-
    -*-
 ----*----------
-***************-
 ----*----------
    -*-
    -*-
    -*-
    -*-
    -*-
    -*-
     -

B = Number of black squares = 25
W = Number of white squares = 48
In each case the number of white squares, W, is about twice the number of black squares, B.

That suggests there's a formula like

W = 2*B + something

or

W = 2*B - something.

Once you've got the formula you should test it out on some other examples.

The total number of squares, T, is given by T = B + W. (The total number of squares is the number of black squares plus the number of white squares.) If you put your formula for W in to the right-hand side of T = B + W you will get a formula for T in terms of B.

Why is that worth doing? Because it tells you how to calculate the area of the "fattened cross" if you know the area of the "original cross".

Jonny W.
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guest
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#9
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#9
Surely the original is like this?
w w w
w b w
w w w b w w w
w b b b b b w
w w w b w w w
w b w
w w w

If there are no extra squares at the corners (like the previous post suggested) then it would not make a cross shape. In this case to the original 9 squares you add 24 then 32 then 40 etc. Try doing it for a cross with longer arms before looking at irregular ones.
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guest
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#10
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#10
Sorry that didnt work!
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Jonny W
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#11
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(Original post by guest)
Surely the original is like this?
w w w
w b w
w w w b w w w
w b b b b b w
w w w b w w w
w b w
w w w

If there are no extra squares at the corners (like the previous post suggested) then it would not make a cross shape. In this case to the original 9 squares you add 24 then 32 then 40 etc. Try doing it for a cross with longer arms before looking at irregular ones.
Your interpretation is more natural, in that the fattened shape looks more like a cross.

It is however not consistent with Vikz13's original post. Your shape contains 33 squares, not 25.

Jonny W.
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