Monday

October 24, 2016
Total # Posts: 1,627

**Math**

a. the radius was how many feet? How many feet in a yard? Then how many feet in 2 yards? b. the diameter was how many feet? The radius is from the edge of the circle to the center. The diameter is edge to center to other edge, so it's twice as far. The diameter is twice ...

*November 5, 2009*

**algebra**

You're welcome!

*November 5, 2009*

**algebra**

Absolutely right all the way. Well done!

*November 5, 2009*

**Math**

Don't let the negatives throw you! You need a common denominator. What's a common denominator of 6 and 10? 60. 9/10 = what/60 ? 1/6 = what/60? Now that you have them both in sixtieths, just add to get your answer. But since they were both negative, your answer will ...

*November 5, 2009*

**arithmetic**

Well, at the 20th term, n is 20. Does knowing that help?

*November 5, 2009*

**physics**

calculate the force of a 300,00 kg jumbo jet that is accelerating 0.4m/square just before takeoff

*November 2, 2009*

**physics**

calculate the acceleration of a 2000kg single -engine airplane just before takeoff when the thrust of the airplane ia 500N Using the G.U.E.S.S. method

*November 2, 2009*

**PreCalc (still confused)**

First thing to remember is that a square is a rectangle; it's just a special case of a rectangle. Getting back to a "mathematical way to go about it", there are two I can think of, and one involves calculus. Maybe this is set to make you appreciate calculus when ...

*November 1, 2009*

**PreCalc (still confused)**

Let me phrase it as a real-life-ish word puzzle: You need to build a pool 400 sq. m. in area. Building curved or slanted sides is too complicated and expensive, so the sides have to be straight, so you're going to make it a rectangle. The sides cost you $10 per metre to ...

*November 1, 2009*

**PreCalc (still confused)**

Good question! 2X+2Y could be equal to lots of things: your question is to find the _minimum_ they can be equal to. For example, we know xy=400 so x=5, y = 80 works for that. Then 2x + 2y = 10 + 160 = 170. That is one answer. x=10, y=40 also gives us xy=400. Then 2x + 2y = 20...

*November 1, 2009*

**math**

You've done the hard part, so you're probably just over-thinking it! :-) When x=2, plug 2 into that equation of the circle, and what do you get? x^2 -4x + y^2 -6y =12 4 - 8 + y^2 -6y = 12 y^2 -6y -16 = 0 and solve for y. Same method works for getting the points where y=3.

*November 1, 2009*

**maths**

The sin of an angle is opposite / hypotenuse We know the hypotenuse. We know the angle, so ee can get the sin of the angle. Set sin(35)= x/13 and solve for x.

*November 1, 2009*

**Algebra**

There isn't an "easy" factorisation for 5x^2+2x-1, so you can use the formula for the factors of ax^2 + bx + b (-b +- sqrt(b^2-4ac)) /2a but I'm not quite sure why this proves the domain. In the second part, I think I agree with you, but it depends where you ...

*November 1, 2009*

**math- Algebra 2**

OK. First, what exactly is the question? How many seats in the last row? How many seats in the auditorium? Let's figure a model to start. Row 1: 40 Row 2: 43 Row 3: 46 Row 4: 49 and so on. We want a formula that, given the row, will tell us how many seats. Multiplying the ...

*November 1, 2009*

**algebra**

What exactly is the question?

*November 1, 2009*

**Math**

Already answered below by bobpursley for "Lila"

*November 1, 2009*

**Math**

Already answered below by bobpursley for "Lila"

*November 1, 2009*

**bobpursley - Oops**

I just overtyped your name into the from rather than the subject.

*November 1, 2009*

**English**

Well, you started out with a perfectly good What. When have people been starving since? Where are people starving? (or where used they starve, or will they starve?) Why do people starve today? (And while lack of food is the simple proximate answer, you can go back a step and ...

*November 1, 2009*

**English**

It may be simplistic, but I've always found the W (and one H!) questions useful for separating out issues: What? When? Where? Why? Who? Whether? Which? How?

*November 1, 2009*

**math- Algebra 2**

You're welcome!

*November 1, 2009*

**math- Algebra 2**

It just means, add: the value of (10k-8)(6k+7) when k=1 plus the value of (10k-8)(6k+7) when k=2 plus the value of (10k-8)(6k+7) when k=3 plus ... (and so on, 4, 5, to 9, 10)... the value of (10k-8)(6k+7) when k=11 plus the value of (10k-8)(6k+7) when k=12 So you could just do...

*November 1, 2009*

**books**

It's a bit unfair asking for help with the NPR puzzle of the week, isn't it? :-)

*November 1, 2009*

**Science**

There are some ideas at Biographies for Kids. You can get there by typing "garden of praise" "Biographies for Kids" leaders scientists (with the quotes) into Google and then going quite a way down the page until you come to the scientists - though I think a...

*November 1, 2009*

**Math**

OK. That's the first sentence covered in x+2y=56 . In 8 years time, the son's age will be half of john's age. If x is John's age now, then his age in 8 years is (x+8), and his son's will be (y+8). So the next thing is to make a second equation from that ...

*October 31, 2009*

**math 10**

Answered below.

*October 31, 2009*

**Calculus**

(x+5)/(x - 3) is just (x+5) ----- (x-3)

*October 31, 2009*

**Calculus**

What is 8 divided by zero?

*October 31, 2009*

**Calculus**

No, it's not wrong. When x=3, we have: (x + 5) / ( x - 3) = (3 + 5) / ( 3 - 3) = 8 / 0 which is undefined, because of division by zero.

*October 31, 2009*

**Sameul**

It can be factored, but not into integers like (x-1); more like sqrt(2)+-1, and it's definitely not a perfect square. I suspect you've got one of the signs backwards in your head, and you'll probably recognise that as we work through it. Anyway, direct ...

*October 31, 2009*

**alegebra 1**

Given two points, the slope is easy: it's the difference in the ys divided by the differences in the xs. Just be careful to get the numbers in the right order and careful of the signs. For example, (3,5) and(2,-2) x1=3 x2=2 y1=5 y2=-2 So the slope is (y1 - y2)/(x1 - x2...

*October 31, 2009*

**C programming**

Ok, so you need to test all a, b, c from 1 through 100 for a*a + b*b = c*c. What point would you like help with?

*October 31, 2009*

**Physics!**

30.6 cm seems to have become 30.6 m instead of .306 m. Does this solve your problem?

*October 31, 2009*

**Language Arts**

I can't post a link but dictionary reference com gives strat-uh-fahy and also the IPA which I will try to post here /ˈstrætəˌfaɪ/

*October 31, 2009*

**PreCalc**

"two sides that are equal and two other sides that are equal" is a good start. Call the length of one type of side x, and the other y. Then the area is x * y And the perimeter is 2x + 2y Check this on a small 5 * 3 rectangle, to be sure you understand it. We are told...

*October 31, 2009*

** SQL for Business**

OK. Do you have a table to test on? Here's a statement that might get you going: SELECT Supplierid, SUM(Count) FROM Part WHERE Count > PARAMETER GROUP BY Supplierid If you just run this against your table, substituting some number in for PARAMETER for now, you should ...

*October 31, 2009*

**SQL for Business**

Which part or concept or keyword are you having problems with?

*October 31, 2009*

**algebra 2**

Count from -9, -8, -7... to 2, 3 Where is halfway?

*October 31, 2009*

**high school math**

I presume you want to multiply it out? (1+2y)(3+5y) = 1 * (3+5y) + 2y * (3+5y) = 3 + 5y + 6y * 10y^2 and you can finish

*October 31, 2009*

**gr 9 math**

I got my PC to run up a hundred of each type. If you want something else, let us know. -10x^2 -27x -18y^2 6x^2 + 30x -36y^2 32x^2 -16x -30y^2 -28x^2 -85x -22y^2 -40x^2 + 21x + 49y^2 27x^2 -33x -4y^2 -36x^2 -6x + 90y^2 15x^2 -13x -20y^2 -24x^2 -95x -50y^2 -25x^2 + 60x -35y^2 ...

*October 31, 2009*

**gr 9 math**

What kinds of polynomials? Can you give an example, please? Something like 7x^2 + 46x + 24 y^2 that factors into (ax+by)(cx*dy), or something like 6x^5 + 21x^4 + 13x^3 - 10x^2 -78x -36, that factors into (3x^3+2x-12)(2x^2+7x+3) Or something else?

*October 31, 2009*

**math**

Bring everything to feet as a unit, so the cartons are .5 * .5 * 1 cu. ft. = 0.25 cu.ft. For the tank, it's pi r^2 h again: pi * 16 * 8 = 128 pi cu. ft. So how many containers will that fill?

*October 31, 2009*

**Literature**

I'm inclined to think that that last sentence implies omniscient; a third-person limited narrator could not say what the protagonist knew. IMHO, of course :-)

*October 31, 2009*

**math**

volume of cyl: pi r^2 h but if h = d then h = 2r, so pi * r^2 * 2r = 2pi * r^3 Vol of hemisphere = (1/2) volume of sphere: = 2/3 pi r^3 So the ratio is obvious from those results.

*October 31, 2009*

**Math**

volume cylinder = pi r^2 h = pi * 5^2 * 29 = pi * 725 volume sphere - (4/3) pi r^3 = pi * 4/3 * 5^3 = pi * 500/3 and you can finish

*October 31, 2009*

**Grammar and Composition**

Wow. You only know 21 words you don't know? :-) I've always liked aglet and dottle, myself. Anyway, there's quite a fun site called freerice - I can't post a link here but if you Google that word or add the most common dot after it, that is com, you'll get ...

*October 30, 2009*

**Algebra**

I think maybe you're getting two concepts mixed up, but I'm not quite sure. The _domain_ is the set of values x can take. That is every real number_except_11, since it's undefined at x=11. The _solution_ to (8x+3)/(11-x) = 0 (aka the y-intercept of the graph) is x...

*October 30, 2009*

**math**

Your answer is not wrong, but it isn't "a fraction in simplest terms", because you've brought in a decimal approximation. Go back a step, to -87 / (-6/7) which is where you were before you detoured into decimal-land. Dividing by 6/7 is the same as multiplying...

*October 30, 2009*

**Algebra 1A**

7 x + 2 <30 Subtract 2 from both sides: 7 x < 28 Now divide across by 7, and finish,

*October 30, 2009*

**math 5th**

Between 2 and 4 yards, and A multiple of 0.5. No integer can be the answer, because it wouldn't divide evenly into 24.5. The only two possibilities are then 2.5 and 3.5. Which is it?

*October 30, 2009*

**Pre-Calculus**

I think you mean 9 cos (pi * x /6) where x is the month number 0 through 11. And very neat that snswer is. It provides a low of 2 and a high of 20. Mind you, you might want to mention that your actual answer is: 1,000,000(9cos(pi/6) + 11) or 10^6(9cos(pi * x/6) + 11) to make ...

*October 29, 2009*

**calc**

It all looks OK to me, except from 1 to e^4 you should have your signs the other way around: ln(1+ln(e^4)) - ln(1+In(1)) ... =~ +1.60944

*October 29, 2009*

**trig**

Ask yourself this: 1. If x>0, is |x - 2| - |x + 2| positive or negative or zero? (or think of it as "is |x - 2| > |x + 2| ?" 2. If x==0, then clearly |x - 2| - |x + 2| is zero. 3. Now, the interesting one: what if x is negative? Then is |x - 2| > |x + 2| ?

*October 28, 2009*

**physics 8th grade**

If a woman hasa mass of 50 kg calculate her weight in neutons

*October 28, 2009*

**math**

Your first answer, y = x + (1/x), is absolutely right. I don't understand why you would think that a square would be involved. Bringing in the square makes it a completely different thing, and that's why you're getting different results on your graphing calculator...

*October 28, 2009*

**Algebra**

You can't separate the added parts and take the square root of each. (You could if they were multiplied, but not if added.) I will show a counterexample. You were looking at sqrt(x^2+1). Consider this example - let x=3, then we have : sqrt(3^2+1) = sqrt(9+1) = sqrt(10) Now...

*October 28, 2009*

**Algebra I**

You've got the 2w bit right, but you haven't followed through on your original equation. Divide 2w^3 by 2w Divide 6w^2 by 2w Divide 4w by 2w Put 'em all back together. What have you got now?

*October 28, 2009*

**Math**

To graphing a straight line: 1. Draw your axes. 2. Set x=0 in your equation to get the y-intercept: x + y = 1 0 + y = 1 y = 1 so we have one point: (0,1) 3. Set y=0 in your equation to get the x-intercept: x + y = 1 x + 0 = 1 x = 1 so we have a second point: (1.0) 4. Mark the ...

*October 28, 2009*

**college**

Assume you are performing the calibration step of Experiment 8 and you begin with 80 g of water at 20 oC and 80 g of water at 80 oC. After adding the two portions of water into your calorimeter setup and following the procedure outlined in the experiment, you determine the ...

*October 28, 2009*

**chemistry**

Assume you are performing the calibration step of Experiment 8 and you begin with 80 g of water at 20 oC and 80 g of water at 80 oC. After adding the two portions of water into your calorimeter setup and following the procedure outlined in the experiment, you determine the ...

*October 28, 2009*

**math**

You're welcome!

*October 28, 2009*

**math**

2y^2-y(3-2(y-4)-y) Get rid of the inner brackets: 2y^2 - y(3 - 2y + 8 -y) Multiply the y into the brackets: 2y^2 - (3y - 2y^2 + 8y - y^2) 2y^2 - 3y + 2y^2 - 8y + y^2 Now collect the terms together.

*October 28, 2009*

**MATH/SCIENCE**

Easha has the right idea. You need to get all the inputs and outputs into the same units. There's water entering the lake, and there's water leaving the lake. The numbers are just given in different units, which is common in the real world! There's nothing ...

*October 28, 2009*

**MATH**

In each of them, find some factor all the terms have in common. Take #2 for example: 5a^2 - 25a^3 Well, both divide by 5, so we have: 5(a^2 - 5a^3) but we can also take a^2 out of the expression inside the brackets: (a^2 - 5a^3) = a^2*1 - a^2 * 5a = a^2(1 - 5a) So the whole ...

*October 27, 2009*

**math**

I don't think those equations came out right.

*October 27, 2009*

**Calculus**

Just from looking at 2x^2+10x and that has to be zero - I'd try -5

*October 27, 2009*

**math**

1 inch =25.4mm. That is right. But when squaring, you have to square both the units _and_ the numbers, so 1 inch = 25.4 mm (1 inch)^ = (25.4mm)^2 (1^2) inch^2 = (25.4^2) mm^2 1 in^2 = 645.16 mm^2 Or think of it this way: Draw a 3-inch line. That's 3 inches. Now make a ...

*October 27, 2009*

**programming language**

OK, my conscience nags me about that double. To do it right, then instead of taking the lazy way of converting to doubles, and comparing, then: if your current smallest is, say, 13/6 and your new line is, say, 27/13 you should do the comparison by finding a common denominator...

*October 27, 2009*

**programming language**

One approach, simple but with a caveat or two: You need a double for "smallest absoulte ratio so far". Initialise it to something very big. As you take in each line, a) calculate the surface and the volume as two integers b) calculate the absolute ratio as a double c...

*October 27, 2009*

**pre calculus**

Think of it as two curves to draw. One starts at x just greater than 0, somewhere in negative y, passes through (1,0) and (2,3) and off to infinity at x=3. The other comes down from infinity at x=3, passing through (4,3), and just touches the x-axis at a turning point (5,0) ...

*October 26, 2009*

**geometry**

We can't answer without knowing more, like what s is, and whether s is a unit of length or of area.

*October 26, 2009*

**Math**

"maximum: 8, range: 6" gives you your minimum number, so pencil that in, and 8 at the other end of course to make your maximum. Now, if you know what mode and median mean, you should be ready to write in some 6s, and spread about the same number of lower digits.

*October 26, 2009*

**Math**

More like substitution. You already worked out the hard bit: 1.25x + 0.75y = 129.75 and Reiny pointed out that y = 117-x So you can replace (substitute) y in your equation: 1.25x + 0.75(117-x) = 129.75 and I'm sure you can see your way home from there.

*October 26, 2009*

**math**

You can do this with an equation. Let one of the numbers be x. Then the other is (70-x). And we know that x(70-x) = 1224 So -x^2 + 70x = 1224 and solve the quadratic from there. Another way is to list the prime factors of 1224, and guess your way through. Hint: 17 is a prime ...

*October 26, 2009*

**math**

I'm with Zava on the idea, but I think one of us dropped a sign along the way. And I'm not at all sure it wasn't me, so I'll check at the end. Dropped signs happen all the time. We have: x + y = 5 but we're also given what y is: y = x - 3 So we can just ...

*October 26, 2009*

**math**

please help, I have a test tomorrow and i don't get this. solve by substitution 1. y = x - 3 x + y = 5 2. 5x + 2y = 0 x - 3y =0

*October 26, 2009*

**Math**

Oops: that last line should have been = 6.3 * 10^9 of course!

*October 26, 2009*

**Math**

Yes, but "scientific notation" is often used when talking about powers of 10, like: 20000 = 2 * 10^4 This makes arithmetic with large numbers easy, since, following the rule above, all you have to do is add powers to multiply the factors of 10, like: (2.1 * 10^5) * (...

*October 26, 2009*

**Math**

I'll try to answer the case I think you're asking about. If I'm guessing wrong, do ask again. If you have something like x^2 * x^3 (x-squared times x-cubed) then you add the exponents: x^2 * x^3 = x^5 Similarly, in general, x^a * x^b = x^(a+b) With negative ...

*October 26, 2009*

**Algebra 1**

We know that y = mx + c where m is the slope, so the equation we're looking for has to be y = (1/5)x + c (or y = x/5 + c, which is easier to write n this board!) Now all we have to do is find c. We know that (5, -1) must satisfy the equation, do to find c: y = x/5 + c -1...

*October 26, 2009*

**math**

There are two things here. I think you dropped a sign along the way. You have y2 - y1 = 5-1 whereas I think you meant y2 - y1 = -5-1 When you fix that, you still need to find the y-intercept c to finish the whole equation.

*October 26, 2009*

**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*