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1d
comment Graph of f(x) = the first number in the decimal expansion of x
possible duplicate of Graph of the function $f(x)=$the 1st number in the decimal expansion of $x$
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comment Signifcant Figures — Why are rules for multiplying and adding true?
Think about multiplying $1.3 \cdot 1.0002$ The relative error on $1.3$ is $\frac {0.05}{1.3} \approx 0.04$ The relative error on $1.0002$ is much smaller. It would still be true if we were multiplying $0.0000013$ by $10002$ The relative error on the first is much larger.
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comment Signifcant Figures — Why are rules for multiplying and adding true?
Because relative error is more useful to get the final result. If the factors have very different magnitudes it becomes hard to compare $x \epsilon$ and $y \delta$ to $xy$ but you can just add the relative errors to get the error in the product.
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answered A math question related to creating a risk formula..
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answered Signifcant Figures — Why are rules for multiplying and adding true?
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comment How do I multiply $2(\frac{4}{y})$?
@TheAsker: multiply by $y$ and you have a quadratic. You can factor it or use the quadratic equation.
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comment Hanoi Algorithm With Different Nodes
The drawing is exactly what I was seeing. I think the statement that more than three disks cannot be moved to end is correct.
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comment Hanoi Algorithm With Different Nodes
I don't think you can do more than three. The first disk moves to 3, the second to 2, the third plays through. If you have a fourth you are done.
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comment Hanoi Algorithm With Different Nodes
Then I don't think you can do the problem at all for reasonably large $n$. You will get stuck. Note that in the usual tower of Hanoi the edges are bidirectional
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answered Hanoi Algorithm With Different Nodes
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comment How can I know the time difference between two cities by knowing the distance between them and earth speed?
Even if they are at the same latitude, the arc distance is a great circle. What you want is the distance around the parallel of latitude. You can then multiply the equatorial speed by the cosine of the latitude to get the rotation speed at that latitude.
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answered Compound Interest - Initial Amount Borrowed
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revised Vocal group no two singer stand next to each other?
correct typo
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comment Continuity of $f$ define by $f(x,y)=\frac{x^2+y^2}{\tan(xy)}$?
It is not even defined on the $x$ and $y$ axes (except the origin). How can it be continuous?
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revised Verify my answer: show a bijection from (0,1) into [0,1]
added 30 characters in body
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revised Verify my answer: show a bijection from (0,1) into [0,1]
correct
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answered Verify my answer: show a bijection from (0,1) into [0,1]
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answered Solving for an angle
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comment Speed and distance formula derivation
What is your question?
2d
answered Finding the percentile of a value given other percentiles