Wednesday

November 25, 2015
Total # Posts: 1,545

**maths**

I answered this below, rather wordily. If there's something else I can explain, do ask.
*October 26, 2009*

**scatter plots**

OK, so you've plotted your points. The linear model assumption is that a straight line will go through them. It won't, of course, because they're not perfectly in a line, but the idea is to create a line that comes as close as possible to them, usually with the ...
*October 26, 2009*

**algebra (check plz)**

d) is not wrong, but it's not in its final form; you have a constant on each side. Subtract one from each side to get rid of the 1 on the LHS and you'll be finished.
*October 26, 2009*

**math**

You'd recognise it. :-) xy < 0 means xy is negative. When x is 1, what values can y have? When x is 5? pi? 1,000,000,000? When x is -1, what values can y have? If the product of two numbers, say x * y, is negative, what do you know about those numbers? One is p------- ...
*October 24, 2009*

**math finals**

15. and 16 are the answers I got for these questions for margie_o a few days ago, but I see I didn't agree with 18.8% then either.
*October 24, 2009*

**Math Analysis**

You probably took a wrong turn in what was included inside the fourth root. Easy turn to miss. :-) f(x)=(3/4)x^4 g(x)= ((108((3/4)x^4 + 2)-216)^(1/4))/3 = ((81x^4 + 216 -216)^1/4) /3 = ((81x^4)^1/4) /3 = 81^(1/4)x^(1/4) /3 = 3 x / 3 = x
*October 24, 2009*

**math115**

Yes!
*October 24, 2009*

**math115**

You can also do it by getting the prime factors of each: 15 -> 3, 5 24 -> 2, 2, 2, 3 44 -> 2, 2, 11 Now, your LCM must contain all the numbers from any one of those lines. Start by selecting any line, say 15: 3, 5 Now add anything else yu need from 24: 2, 2, 2, 3, but...
*October 24, 2009*

**math115**

15 ad 24 go into 360 evenly. Does 44?
*October 24, 2009*

**equations**

If they're sratring at x = 1 -> Y1 = 1997 , then x = 2 -> Y2 = 1998 then you can just count for a) and b) In the formula y = mx + c, m is the slope and c is the y-intercept, which should answer a couple of them. f) Once you've counted to 2018, just let x equal ...
*October 24, 2009*

**College Algebra**

You're right so far, which was the hard bit. Me, I'd just pull out the calculator at this point. I did, and got 67.2972 = 67.30 to 2 d.p. You can do it by = 29 * sqrt(sqrt(29)) or by log tables. I can't think of an especially clever way.
*October 24, 2009*

**math**

I get 1/(x-3)(x+3) = A/(x-3) + B/(x+3) 1 = (x+3)A + (x-3)B 1 = x(A+B) + 3A -3B -> A + B = 0 -> A = -B -> 3A - 3B = 1 -> A = 1/6; B = -1/6 = (1/6)(x-3) - (1/6)/(x+3)
*October 24, 2009*

**Math **

On what grounds do you choose d?
*October 24, 2009*

**Math **

No, c is not correct. In each of the other cases, what happens when x is the number given: a) 8/(10-90/9) b) x < 10/9, say 1/9 -> 8/(10-9/9) d) 8/(10-72) One of these three is undefined. Which?
*October 24, 2009*

**Pre Calc still confused**

Oops. Left off the last equals: 6.5/1.5 + 6/(1.5-4)+7/(1.5^2-4*1.5) = 0.066666...
*October 24, 2009*

**Pre Calc still confused**

OK. If it's (x+5)/x + 6/(x-4)=-7/(x^2-4x) then I agree with bobpursley's answer but the numerical answers aren't exactly -17/2 and 3/2; they're (-7+-sqrt(101))/2. If you plug 3/2 in, it'll be close but not zero. 6.5/1.5 + 6/(1.5-4)+7/(1.5^2-4*1.5)
*October 24, 2009*

**Pre Calc still confused**

Are the brackets right? I've tried (x+5/x)+(6/x-4)=(-7/x^2-4x), and (x+5)/x + 6/(x-4)=-7/(x^2-4x) and a couple of other permutations without achieving enlightenment.
*October 24, 2009*

**algebra**

We need a variable for the time. Let's call that t. And we can call the distance d. At t = 0 (1pm) you are 150 miles away, and as t increases, the distance decreases, so we need to subtract some multiple of t from 150 as we go. We need something that starts with d = since ...
*October 24, 2009*

**math**

Correct! Perpendicular lines have slopes that are negative reciprocals of each other. Thus perpendiculars of y = -(1/2)x + anything will have a form like y = 2 + something The two lines you specified are in fact parallel, because they have the same slope : (y = -x/2 + something)
*October 24, 2009*

**math**

It would!
*October 24, 2009*

**Trig**

I suspect you mean tan((m + n)/2) on the RHS
*October 24, 2009*

**pre calc**

Not sure you should go by me, because I took it down wrong the first time, but I got: x + 11/x - 4 + 7/x^2 + 4x = 0 Gathering and multiplying by x^2: 5x^3 - 4x^2 + 11x + 7 = 0 Does this makes sense to you in the context of your course?
*October 24, 2009*

**programming**

The confusion may be coming from trying to take in too many things at once. At root, all this is asking is for you to write a function to find a sequence like {8, 7} in a sequence like (1, 2, 3, 4, 5, 6, 7, 8, 9, 8, 7, 6, 5, 4, 3, 2, 1} - which is essentially the same process ...
*October 24, 2009*

**Math**

Which functions are exponential? A)3x B)3^x C)3x^2 D)2^-x I think that B and C are exponential. Am I correct?
*October 23, 2009*

**Physics**

As the time required to run up the stairs increases, the power developed by that person Increases, decreases, or remains the same. Is the answer decreases?
*October 22, 2009*

**algebra**

y = mx + c, where m is the slope and c is the intercept. You are told m, and you are told c, so all you have to do is plug them in.
*October 22, 2009*

**algebra**

y = mx + c, where m is the slope, and c is the y-intercept. You have y = -9x + (-7) So, thinking of it that way, what is the slope and intercept?
*October 22, 2009*

**algebra**

I didn't get it either, until I erad the question for the equation three times. It seems they're assuming that the life expectancy function plotted agaist the years since 1990 is a straight line, and I'm not at all sure you should assume that. Anyway, if we do ...
*October 22, 2009*

**math 115**

So plot your amount spent along the x-axis and your sales on the y-axis, and extend the line out to $50. Nt much else we can help you with on this one.
*October 22, 2009*

**algebra**

he slope is just the difference in the ys over the differences in the xs. That is, when you move 1 in the x direction, how far do you move in the y direction. -4 isn't very far off, but it's not the exact answer: Your Ys are 13.4 and 2.1 Your Xes are -19.3 and -17.3 (...
*October 22, 2009*

**math(rational functions application)**

Call the speeds j and c. j - c = 100 -> j = 100 + c (100 + c) = 5c / 4 (from the "25% faster") Solve for c.
*October 22, 2009*

**algebra**

If I understand the question, 10, 12, 14 and 16 is not right. Is 2 * 10 + 16 = 96? Call the numbers a, b, c, d. We're really only interested in a and d. How much bigger is d than a? d = a + ? Call the unknown x. d = a + x Now, we know that 2a + d = 96 but we also know that...
*October 22, 2009*

**corp. finance**

It's tedious, but there isn't a useful shortcut. In year one, you add 13% of 5000 to the 5000, making 5650. Then you add 3500, making 9150. Then you add 13% to that, and then add another 3500, and go for another year @ 13%. And so on.
*October 22, 2009*

**math**

Would you fit a billion gallons of gas in your tank? Could you afford to? Would you stop to buy 1 thousandth of a gallon? The appropriate domain will be somewhere inbetween. You figure out what, based on your own good sense. Given your domain, the range easily falls into place.
*October 22, 2009*

**Math**

What is their combined speed approaching each other? The two cover all but 240km of the 3600. What is that distance? Divide the distance by the speed to find how long.
*October 22, 2009*

**math**

Imagine you're dividing the money into equal piles, and you're giving 2 piles to the first 4 piles to the second 6 piles to the third How many piles do you need? How much money is in each pile? Now, how much money does each get?
*October 22, 2009*

**math**

Imagine you start with $1 (or $1,000 if you prefer). How much would you have at the end of two years, under each of the schemes? For example, under the second, starting with $1, you would have $1 * 1.06 = $1.061 at the end of the first year $1.061 * 1.06 = $1.12466 at the end ...
*October 22, 2009*

**Pre- Caluculus**

So what is the depth when full, when t=0? We want to make sqrt(100-2t) = half of that, which is 5. sqrt(100-2t) = 5 Square both sides. Subtract 25 from both sides. Now t is easy.
*October 21, 2009*

**..**

Mind you, the physicists proved it didn't exist back in 1887, so maybe you're imagining that!
*October 21, 2009*

**..**

Ineluctably ineffable, even.
*October 21, 2009*

**english**

Which is a theme of both “One Thousand Dollars” and “By the Waters of Babylon”? -Things are not always what they seem to be -If you do what is forbidden, you will pay the price. -Love can change the world -Life is not always fair.
*October 21, 2009*

**Critical Thinking**

A valid syllogism is: All A are B C is A therefore (since C is A and all A are B) C is B The non-syllogism above is: All A are B All C are B Therefore all A are B. Erm, no. Spot the difference. Here's one of the same form: All fish are animals All birds are animals ...
*October 20, 2009*

**Algebra**

Personally, I'd do those backwards from c, and I was taught to sketch graphs using a different method, so maybe someone else will be more in tune with your text. Anyway, following these steps: a) Start with a table of values. This function is most interesting in x [-3, 3...
*October 20, 2009*

**Math**

The commutative property of multiplication says that xy=yx. The commutative property of multiplication says that (x^2)+(y^2)=(y^2)+(x^2) That's all you need, though you can draw it out with substitutions if you want.
*October 20, 2009*

**math algerbra**

You'd need to post your work here for people to check, or at least tell us what kind of problem it is, to think of the best ways to check that kind of algebra.
*October 20, 2009*

**math**

Distributive property says, for example: 4 * 3.14159 + 5 * 3.14159 =(4 + 5|) * 3.14159 = 9 * 3.14159 that should give you the idea. And the second one is the same idea.
*October 20, 2009*

**MATHS**

There's the weight of the truck, and the weight of the papers. The weight of the truck doesn't change ever. The weight of the papers depends on how full the truck is. Let P be the weight of papers if the truck is full, tyhen: T + (1/2)P = 1762kg. T + (1/4)P = 1426kg. (...
*October 20, 2009*

**Math Analysis**

You don't multiply the co-ords, exactly. What you're scaling is the coefficients. But careful: f(-2x) is not -2f(x)! f(-2x) means might be a shorthand for f(g(x)), where g(x) = -2x. -2f(x) would be -2(3/4)x+2(3/2) =3-(3/2)x Your parabola is y=x^2, or f(x) = x^2 so 2f(x...
*October 20, 2009*

**Math Analysis**

OK. The original function is f(x)=(3/4)x-3/2 1. Yes, the function (3/4)x + 1/2 does pass through those points (-2,-1) and (2,2), as you can verify by plugging them in 2. You're right; there is no amplitude - but there is a slope! It doubles the slope, and the y-intercept. ...
*October 20, 2009*

**math**

Actually, what yu've written is a bit of both. Commutative is: 4 + 5 = 5 + 4 Associative is: (4 + 5) + 2 = 4 + (5 + 2) So 4 * (7*5) = (4*7) * 5 is Associative. but 5*7 = 7*5 is Commutative.
*October 20, 2009*

**Math**

We are given: (a) E = 2M and (b) E-3 = 3(M-3) So: 2M - 3 = 3M - 9 solve for M.
*October 20, 2009*

**Math**

In case you ever come back to this, I just saw MathMate answering the same question, but reading "6% compounded monthly" as "6% _per annum_ compounded monthly". This makes it a whole different question, and incidentally brings the interest rates back into ...
*October 20, 2009*

**Math**

P.S. Yes, this would mean that if you started with $4,000, at the end of the year, you would have $4,000 * 48482.72 = $193,930,880 (and you took the measly 6% per month? :-)
*October 20, 2009*

**Math**

Right. It's not 1.03*365. It's 1.03 to the power of 365 aka 1.03^365 also written 1.03 with 365 written in superscript above and just to the right of 1.03. The power key isn't on all calculators. Scientific calculators usually have this function, and it's ...
*October 20, 2009*

**Math**

You have to take the 4000, and add 3% for the first day and then add 3% to your answer for the second day and then add 3% to your answer for the third day How do you add 3%? Multiply by 1.03. So just take your 4000 and multiply it by 1.03, and repeat the multiplication 365 ...
*October 20, 2009*

**Math**

Look at my second explanation. That takes it one step at a time. Each month, you have 1.06 as much as you had the month before, so at the end of the 12 months you have 1.06*1.06*1.06*1.06*1.06*1.06*1.06*1.06*1.06*1.06*1.06*1.06 as much as at the start. That is 1.06 to the ...
*October 20, 2009*

**Math**

Or you could so it this way: Start with one dollar. Add 6% to it. Add 6% to that. Add 6% to that. and so on for 12 months. At the end, you have $2.01 (ignoring rounding). $1 of that was your principal, so $1.01 is interest paid during the year, which is 101%.
*October 20, 2009*

**Math**

(1.06^12 - 1) * 100
*October 20, 2009*

**Math**

And for b. yes.
*October 20, 2009*

**Math**

Think of it this way: After 1 month, you're 6% up, which is an extra 240. Next month, you get 6% of 4240, which is an extra 254.40, and you throw that into the pot. Next month, you start with 4494.4, and throw another 6% onto that again. Working through an example like ...
*October 20, 2009*

**Math**

It would be 4000 * 1.06^6, which is 5754.08 after six months.
*October 20, 2009*

**Math**

One reason I'm leery of this question is "6% compounded monthly". If that's supposed to mean 6% per month, which is what it seems to mean, it's a crazy interest rate, over 100% p.a. (3% compounded daily is even crazier! Waay crazier!) a. Anyway, in ...
*October 20, 2009*

**CRT/205 critical thinking**

I can't see how it could be a useful argument at any level. Even if you removed the species confounder it would reduce to "Withdrawal is a side-effect when going through the process using a blocker, THEREFORE there will be no withdrawal when not using the blocker.&...
*October 20, 2009*

**CRT/205 critical thinking**

I wasn't being sarcastic. The version I made up seems to me about equivalent to the original in its logical value. I was, I admit, hard put to come up with something as obviously wrong. Chemical effects on animals and humans (or other animals) are well known to be ...
*October 20, 2009*

**CRT/205 critical thinking**

Premise: Using a rider on a motorcycle, researchers recently have reported head injuries. However, to achieve this effect, researchers also caused a brick wall to jump up out of the ground in front of the motorcycle when it was moving at 60 miles an hour. Conclusion: if a ...
*October 20, 2009*

**math**

I'm guessing that it's a rectangle 15 across and 20 high, with a triangle on its left side, a right-angled triangle, 20 high and 15 at its base, with a hypotenuse of 25. And you need the area. The area of the rectangle is 15 * 20 = 300. The area of the triangle is half...
*October 20, 2009*

**Math**

This is really just like the other one - but simpler. You don't even need the brackets, assuming the question is written correctly: 4^n + 4n -4n^2 + 2^n - 2n (4n - 2n = 2n, sp) 4^n + 2^n - 4n^2 + 2n
*October 20, 2009*

**math115**

After doing a dozen of these answers, I can barely remember that 2+2=5 :-)
*October 20, 2009*

**math115**

I get the same answer as melody on the first one, but please do check my arithmetic: 1/4 hr = 60 / 4 = 15 min 2/3 hr = 120 / 3 = 40 min 4/5 hr = 240 / 5 = 48 min 15 + 40 + 48 = 103 min = 1 hr 43 min
*October 20, 2009*

**algebra**

What do you want done with this? And I suspect you need to add brackets to make the expression unambiguous.
*October 20, 2009*

**math115**

37,41,43 - right! 1/15 - right! 112 - right!
*October 20, 2009*

**math**

Whatever number it is has to divide evenly both by 12 and by 8. For example, could it be 80? Well, that would use up exactly 10 packages of 8 buns, but would it use up exactly some number of packages of hot dogs? So it can't be 80. And similarly, it can't be 50, or 81...
*October 20, 2009*

**Math**

Take it a bit at a time. Write 3(r^2+2p-p^3) so that there are no brackets. Now write -(6r^2+p^3-p) so there are no brackets. Now add both together, bringing together the r^2, p and p^3 terms.
*October 20, 2009*

**Math**

I'm sorry, but I'm still not clear. Maybe it's ((30/5) *( 3-2)) /(2-2/3)) ? That would be (6 * 1) / (4/3) = 6 * 3 / 4 = 4.5
*October 20, 2009*

**Math**

You 'll have to clarify that. Do you mean: 30 / (5*3-2)/ (2-2/3) ?
*October 20, 2009*

**Math**

All right!
*October 20, 2009*

**calculus**

This and the other seem to be similar. Best to talk about the general method. 1. Find an expression for the distance between the two at time t. In this case, with Pythagoras' help, that's sqrt( (25t+30)^2 + (16t)^2) = sqrt(881t^2 + 1500t + 900) Nasty-looking thing. ...
*October 20, 2009*

**Math**

It depends on the person! And how fast they jog, and even what terrain they're jogging over. Jogging might burn 300-500 calories an hour, so anything from 1000 to 1750 in a week.
*October 20, 2009*

**Math**

Do you need extra brackets? Should that be f(x,y)=xy/(x^2+y^2) because without the brackets, the assertion is false.
*October 20, 2009*

**Math **

12-|-13+15| = 12 - 2 = 10 Right.
*October 20, 2009*

**Math**

14. I don't get the same answer. a) Get size of property = 188 * 100 = 18800 b) Get size of lake = pi * 36^2 = 4069.44 c) Get size of island = pi * 12^2 = 452.16 d) Covered in water = (b) - (c) Percentage = (d) / (a) 15. I don't get exactly this answer either, but very...
*October 20, 2009*

**Math**

Yes. 6. Yes. 8. Yes. 9. Yes. 11. Yes!
*October 20, 2009*

**physics**

Correct!
*October 20, 2009*

**Algerbra1**

One. You can tell without calculating because the slopes are different.
*October 20, 2009*

**math**

1. Yes. 2. Yes 3. Yes 4. Yes!
*October 20, 2009*

**math**

1. Correct 2. Correct 3. Close. Associative property. 4. Correct 5. Correct 6: Nope, assumng I'm reading the question right: 7/8 - 9/3 7. Correct 8. Correct 9. 41 and 43 are twin primes 10 Correctamundo. 9.
*October 20, 2009*

**Math**

You go to a cafe with your two friends. You are treating them, and you are all having milk and a cinnamon bagel. That is one such situation. How is the order of operations important? Work out the bill.
*October 20, 2009*

**math**

Right!
*October 20, 2009*

**MATH**

Yes!
*October 20, 2009*

**Math**

Start with 612. Does it divide by 2? Yes. So write it as 306*2 Does it divide by two again? Yes. So write it as 153*2^2 No more 2s. Try 3. Keep going until you can find no more factors.
*October 20, 2009*

**Math**

In logic, "or" means _either one_ of them is true. Maybe one is true, maybe the other, maybe both, but as long as at least one of the statements is true, then the whole statement is true. Given that, cal you see which statements are true? We define "prime number...
*October 20, 2009*

**Math**

I think the answer expected is "exact", but for a different reason. (Unless somebody went missing, or the food was contaminated!) An estimate is going to be high, and you know it will be high: 20 * 40. A closer estimate 20 * 40 - 40 will be low, but close, and what ...
*October 20, 2009*

**physics**

Pythagoras OK, but remember you have to square all the sides. 12.5^2= x^2 + 7.2^2 156.25 = x^2 + 51.84
*October 20, 2009*

**math **

It's just a line between and including the points -4 and 10.
*October 20, 2009*

**Calculus**

I'm not quite sure about the question, but I'll guess. The MVT is about the average slope. The average slope is the slope of the sstraight line between (1, 5) and (4,5), which is zero. I'm guessing you're looking for the point or points in the curve whose slope...
*October 20, 2009*

**Math 350..help!**

Don't let all the digits and decimals throw you off. The number of years after 1980 just means that in 1981, t = 1, and 1982, t = 2, and so on. You need to differentiate 0.07t^3 - 3.1t^2 + 54.3t - 230 Which, really, is just differentiating t^3, t^2, and t and multiplying ...
*October 20, 2009*

**Probability**

I don't think you've given us all the information from the table. Maybe you haven't recognised all of the information. Does "50% of them" means "50% of all employees" or "50% of males"? That makes the question ambiguous, and offhand I ...
*October 20, 2009*

**algebra**

-x / 8 = 3 Multiply across by 8: -x = 3 * 8 Multiply across by -1: x = 3 * 8
*October 20, 2009*

**maths**

1) is what I get too. 2. a) I agree with 69 as well. 63 digits will get you to p36. Another 66 digits will get you another 33 pages. b) When I calculate this, I get 204 digits for 104 pages: 9 digits for 1-9 180 digits for 10-99 15 digits for 100-104 I think you're ...
*October 20, 2009*

**Maths**

Mark is right, but for numbers of the form x0x, you can of course use any digit, not just zero, so 101 also implies 111, 121, 131,....
*October 19, 2009*