by Dudley
(Roseville, CA. U.S.A.)
1. Think of any positive whole number. No fractions, no decimals,no percents.
2. Double that number.
3. Add 10 to that result in step 2.
4. Divide the result in step 3 by 2.
5. Subtract the number in step #1 from the number in step #4.
6. The answer will always be 5.
Let x be the number
Double x : 2x
Add 10 to 2x : 2x + 10
Divide the number by 2: (2x + 10) / 2 = x + 5
Subtract x from x + 5: x + 5 - x = 5
The answer is 5
Example
Let 8 be the number
Double 8: 16
Add 10 to 16: 26
Divide 26 by 2: 26/2 = 13
Subtract 8 from 13: 13 - 8 = 5
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Learn how to derive the equation of an ellipse when the center of the ellipse is at the origin.