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# can someone good at maths please point me in the right direction? watch

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1. I'm doing the number grid coursework for gcse maths, and I need to prove that the difference between two products is always 10. How do I go about doing this? I haven't a clue, and it's due in tomorrow
Any help would be greatly appreciated!
2. (Original post by Cate)
I'm doing the number grid coursework for gcse maths, and I need to prove that the difference between two products is always 10. How do I go about doing this? I haven't a clue, and it's due in tomorrow
Any help would be greatly appreciated!
elucidation required.
3. (Original post by Ralfskini)
elucidation required.
Sorry! OK, you have to multiply the top left number in 2X2 box on a 10x10 number grid by the bottom right number, and vice versa, then calculate the difference between these two products. I have found that the product is always 10, but I don't know how to prove this.
The formula for the overall products of the box is, I think, 2nsquared + 22n + 10
4. I was teaching this to year 8's the other week!

Hold on whilst I work it out.....

Ok.

GRID:

n | n+1
-------------
n+10 | n+11

Product will always be:

n*(n+11) = n^2 + 11n

and

(n+10)*(n+1) = n^2 + 11n + 10

Difference = (n^2 + 11n + 10) - (n^2 + 11n)
= n^2 - n^2 + 11n - 11n + 10
= 10

Thus proved. Ok?
5. I did actually type out a complete solution to this problem but thanks to the ******* server it didnt let me post it.
6. Thanks for your help! As it happens though, by the time the stupid server let me view the thread, I had figured it out anyway Cheers anyway
7. (Original post by Ralfskini)
I did actually type out a complete solution to this problem but thanks to the ******* server it didnt let me post it.
Why don't you try copying it before posting? Also, if you press refresh on the 'server is too busy screen' sometimes it will keep your post.
8. Lol, I can't believe I couldn't figure that out, I feel really stupid now Hehe...

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