Maths question help!!!!

2009-08-05 2:50 am

that's my maths teacher gave : EXPLAIN THE MATHS behind, USE ALGEBRA TO GENERALISE IF POSSIBLE

1. First of all, pick the number of times a week that you would like to have chocolate (more than once but less than 10)

2. Multiply this number by 2

3. Add 5

4. Multiply it by 50

5. If you have already had your birthday this year add 1759 ..
If you haven't, add 1758

6. Now subtract the four digit year that you were born

You should have a three digit number

The first digit of this was your original number
(i.e., how many times you want to have chocolate each week).

The next two numbers are YOUR AGE

回答 (1)

用戶9112

2009-08-05 3:39 am

✔ 最佳答案

1.First of all, pick the number of times a week that you would like to have chocolate (more than once but less than 10)
Let's say pick x
2. Multiply this number by 2
It becomes 2x
3. Add 5
2x + 5
4. Multiply it by 50
(2x + 5) * 50 = 100x + 250
5. If you have already had your birthday this year add 1759 ..
If you haven't, add 1758
1759 = 2000 – 241 so
100x + 250 + 1759
= 100x + 250 + 2000 – 241
= 100x + 2009
1758 = 2000 – 242 so
100x + 250 + 1758
= 100x + 250 + 2000 – 242
= 100x + 2008
6. Now subtract the four digit year that you were born
This is 100x + (2009 – birth year) or 100x + (2008 – birth year)
You should have a three digit number
The first digit of this was your original number
(i.e., how many times you want to have chocolate each week).
Because it is 100x and x < 10, so 1 becomes 100, 2 becomes 200, 3 becomes 300, etc
The next two numbers are YOUR AGE
Current year = 2009 – birth year = age if birthday passed
otherwise 2009 – birth year – 1 = 2008 – birth year = age

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