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• Today, 06:10 PM
A common trick for this sort of thing is to bring in a*b, which can act as a bridge between a*a and b*b. For example, try adding that to each side of...
1 replies | 26 view(s)
• Today, 04:48 PM
No, EBCD is not a permutation of ALL of the letters; it is a permutation of only 4 of the 7 letters. The question asks for permutations of the...
7 replies | 68 view(s)
• Today, 03:19 PM
Were you taught to write your calculations as multiplications of things (rather than of numbers) as you are doing? I don't think it's a safe thing to...
7 replies | 68 view(s)
• Today, 02:53 PM
The word "string" refers to an ordered list (without reference to repetitions). It isn't used as often in math as, say, "permutation", so you can be...
7 replies | 68 view(s)
• Today, 12:05 AM
There is an odd feature of this problem that will not be captured by the equations you will write. If you are writing to us because you had trouble...
3 replies | 128 view(s)
• Yesterday, 08:34 PM
It appears that period means thousands and comma means decimal, so the first payment is $10 000, increasing by$100 each time.
10 replies | 308 view(s)
• Yesterday, 04:44 PM
Yes, that's how I understand it, too. I'm just asking HOW he is "stuck" in doing that. He seems to know of a method (which is mentioned at the...
9 replies | 182 view(s)
• Yesterday, 04:23 PM
Yes, you're on the right track. Keep going in the same direction ... It's nice seeing people who are successfully returning to math.
3 replies | 115 view(s)
• Yesterday, 04:19 PM
That tells you what percentage of the original the new price is. In this case, 400% of $5 is$20. That's the same as "4 times as much".
6 replies | 153 view(s)
• Yesterday, 04:16 PM
Please be precise: What are you doing, exactly? Where are you stuck? What is going wrong? You mentioned earlier wanting a book about such...
9 replies | 182 view(s)
• Yesterday, 02:12 PM
Try first drawing a more accurate diagram (make it an actual angle bisector to get the relationships approximately right). Then construct an altitude...
2 replies | 119 view(s)
• 11-15-2018, 08:13 PM
I'll give you a general idea of what to do. I'll focus on the sales rep. I would first gather information so I can see it all easily: Drives...
4 replies | 246 view(s)
• 11-15-2018, 06:00 PM
I assume you are asking only about the math, not about the details of programming; and that you know at least some of the math involved. You might...
9 replies | 182 view(s)
• 11-15-2018, 12:48 PM
Please consider my hint: How many of these numbers have NO duplicate digits? (Think in terms of permutations, which do not repeat.)
8 replies | 190 view(s)
• 11-15-2018, 12:27 PM
When a problem involves the phrase "at least one", it is often helpful to first calculate the number of ways with "none". That is, how many numbers...
8 replies | 190 view(s)
• 11-15-2018, 10:56 AM
The meaning of "remainder" depends somewhat on context, but here is probably means "least positive residue", and what you say is correct (for the...
1 replies | 194 view(s)
• 11-14-2018, 02:42 PM
It's the net signed area of the "shaded region" -- that is, the sum of a positive area and a negative "area".
1 replies | 131 view(s)
• 11-14-2018, 02:27 PM
First, we need to be sure whether log represents base 10 or something else. (It's used for whatever kind of log is most often used in a particular...
2 replies | 152 view(s)
• 11-14-2018, 02:11 PM
Sounds good to me. You can, of course, check your answer easily enough. For n=3, you know each angle is 60, which is indeed 20*3; and for n=6,...
3 replies | 115 view(s)
• 11-14-2018, 02:07 PM
As I suggested before, there is no one right answer. You might give 56 as your answer, explaining that that is a typical value based on the data so...
5 replies | 319 view(s)
• 11-14-2018, 12:07 PM
There's an easy way to do this: "Unroll" the four walls into a single rectangle, and think about the problem in that new form.
1 replies | 110 view(s)
• 11-14-2018, 12:05 PM
Just for the sake of closure (for anyone who's been following this), could you tell us what the whole problem was?
5 replies | 190 view(s)
• 11-14-2018, 08:52 AM
Is it possible that there is additional information elsewhere than what you quoted -- perhaps in the instructions for a group of exercises, or in a...
5 replies | 190 view(s)
• 11-13-2018, 09:44 PM
The hypothesized value is the value that is hypothesized: that is, the value that is supposed for the sake of comparison. The null hypothesis here...
1 replies | 155 view(s)
• 11-13-2018, 12:56 PM
Take it step by step. Suppose he started with \$100. How much did he spend at store A? How much was left? Then continue. Then you might think about...
2 replies | 258 view(s)
• 11-13-2018, 11:25 AM
It isn't clear exactly what your teacher is asking you to do, and what you did. There are many ways to prove any identity. My impression is that...
3 replies | 249 view(s)
• 11-13-2018, 11:19 AM
I think you confused us by not saying what you were told to take the derivative of! You seemed to be mentioning the simpler sum in passing, as a...
10 replies | 338 view(s)
• 11-13-2018, 12:09 AM
If you don't choose to use logarithms, you can rewrite the equations as 5^x = 2^7 5^(3y) = 2^5. Then raise the first equation to the 5th...
4 replies | 255 view(s)
• 11-12-2018, 10:40 PM
It sounds like you haven't learned anything very advanced, so for the first question they probably expect you to state either the mean or the median....
5 replies | 319 view(s)
• 11-12-2018, 11:57 AM
To be very careful, I might take it like this: There are two cases, depending on whether b is positive or negative. (I'll include zero with...
5 replies | 226 view(s)
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Biography:
I was a software engineer for many years, and have been teaching at a community college since 2004. Since 1998, I was a part of Ask Doctor Math (http://mathforum.org/dr.math/ and now http://themathdoctors.org/).
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Rochester, NY

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