- #1
Trail_Builder
- 149
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hi, I have 2 questions here that I am stuck on. I thought I may as well stick them in the same topic to avoid cluttering the forum. hope you can help, thnx
QUESTION 1
Fred invests an amount of money in an account paying r% compound interest per annum. The amount of money doubles after n years.
Find a formula for r in terms of n.
where m is the initial money]
[tex]2m = m(\frac{100+r}{100})^{n}[/tex]
[tex]2 = (\frac{100+r}{100})^{n}[/tex]
[tex]\sqrt[n]{2} = \frac{100+r}{100}[/tex]
[tex]100\sqrt[n]{2} = 100 + r[/tex]
[tex]r = 100\sqrt[n]{2} - 100[/tex]
now, that seems to be the right answer but looks kinda ugly... first of all, is that answer right? and secondly, if so, is there a nicer way to put it :S ?
thnx
QUESTION 2
Using this result, or otherwise
I proved for the previous question that
[tex](m^2+1)(n^2+1) = (m + n)^2 + (mn -1)^2[/tex]
write 500050 as the sum of 2 square numbers.
I havn't been told how to do this. maybe because this is on a past paper it isn't on the syllabus anymore, but still, I'd like to know how to do it because i doubt its that hard once you know how.
thnx
QUESTION 1
Homework Statement
Fred invests an amount of money in an account paying r% compound interest per annum. The amount of money doubles after n years.
Find a formula for r in terms of n.
Homework Equations
The Attempt at a Solution
where m is the initial money]
[tex]2m = m(\frac{100+r}{100})^{n}[/tex]
[tex]2 = (\frac{100+r}{100})^{n}[/tex]
[tex]\sqrt[n]{2} = \frac{100+r}{100}[/tex]
[tex]100\sqrt[n]{2} = 100 + r[/tex]
[tex]r = 100\sqrt[n]{2} - 100[/tex]
now, that seems to be the right answer but looks kinda ugly... first of all, is that answer right? and secondly, if so, is there a nicer way to put it :S ?
thnx
QUESTION 2
Homework Statement
Using this result, or otherwise
I proved for the previous question that
[tex](m^2+1)(n^2+1) = (m + n)^2 + (mn -1)^2[/tex]
write 500050 as the sum of 2 square numbers.
Homework Equations
The Attempt at a Solution
I havn't been told how to do this. maybe because this is on a past paper it isn't on the syllabus anymore, but still, I'd like to know how to do it because i doubt its that hard once you know how.
thnx
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