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October 25, 2014

Posts by Noether


Total # Posts: 34

geometry
The volume of a sphere with radius r is (4/3)(pi*r^3). Use that.
December 1, 2009

General
What's the proper way to reference a book from Project Gutenberg (MLA format)? It doesn't have all the information for the book format, but it was originally published as a book, so the web page format doesn't seem right. (If it matters, the book is Lewis Carroll&#...
December 1, 2009

Science
When an antibiotic is used, some of the bacteria may be more able to survive it than others. The more-resistant bacteria survive to reproduce and pass their resistant genes to the next generation. The less-resistant bacteria don't get the chance to reproduce. Therefore, ...
February 4, 2009

Algebra
Looks right to me.
February 4, 2009

physics
That's probably because of significant figures. 15.0 m and 95.0 N both have three significant figures. Therefore, the answer should also have three significant figures. 1425 rounded to three sigfigs is 1430.
February 4, 2009

math
(88-8)*8
February 4, 2009

Algebra
Not quite. In your first step, you aren't doing the same thing to both sides of the equation. 5x-3 = 11+12x You correctly recognized that you need to isolate the x terms on one side. However, if you subtract 12x from the right, you need to subtract 12x from the left, not ...
February 1, 2009

Algebra
No, 40 is right. [8(6 - 1) - 1] - [2 - (5 - 2)] [8(5) - 1] - (2 - 3) 40 - 1 - (-1) 40
February 1, 2009

double check me please. math 012
(4)(5-w)/3 = -w (20-4w) / 3 = -w 20/3 - 4w/3 = -3w/3 20 - 4w = -3w 20 = w. Looks right to me.
February 1, 2009

math 012 double check me please
Your first two steps are fine. On the third, in which you go from 12x - 12 = 10x - 43 to -12 = -2x - 43 I think you mean to say you're subtracting 12x from each side. Adding 43 to each side leaves 31 = -2x. Divide each side by -2 to get x = (-31)/2. So, it looks like you ...
February 1, 2009

math 012
Your mistake here is when you go from 16y + 8 = 10 + 12y to 8 = -6 + 12y. You aren't subtracting the same thing from both sides; you're subtracting 16y from the left, but 16 from the right. Assuming you mean to subtract 16y, you should end up with 8 = 10 - 4y Subtract ...
February 1, 2009

Algebra
There's not enough information here to answer those. There are infinitely many functions that sent 9 to 2. For example, it could be f(x)=(x/3) - 1, f(x) = (x-1)/4, f(x) = x-7, f(x) = x^2 - 79, f^x = x^(1/2) - 1, f(x) = 2x-16, or any of infinitely many others. We need more ...
February 1, 2009

Algebra
That's correct. I think it might be better if you made it clearer in your explanation that you did 70 + (7*45); as it stands now, somebody reading the explanation might think you meant you did (70+7) * 45.
February 1, 2009

math
Oops. Switch l and w in that last line.
February 1, 2009

math
A = l * w. A = 1050 ft^2 w = 15 ft. w = A / l = (1050 ft^2) / (15 ft) = ?
February 1, 2009

math
The key fact here is that (at least on a plane) the angles of a triangle add to 180 degrees. So we have three angles, of measures x, x, and x+15. We can set up the equation 3x+15 = 180. Solve for x, and figure out which of the three angles is the largest (If figuring out which...
February 1, 2009

Algebra
Note: This answer assumes the expression is parenthesized as (x^2 - 4) / (x^2 - 4x + 4). Either you made a mistake, I did, or the book did. The graph of that expression doesn't have a hole. It does, however, have a vertical asymptote at x=2. Are you sure you're ...
February 1, 2009

Algebra
Those actually both use the same method, the one you described for the second example. x=(-1) makes (x+1) equal to zero, and x=1 makes (x-1) equal to zero.
January 25, 2009

algebra
Your answers aren't right. You can check factorizations pretty easily by just multiplying. (3w)(3 - w^2) = (3w)(3) - (3w)(w^2) =9w - 3w^2 ((m-n)^2)((m-n)^2) = (m-n)^4 =/= m^4 - n^4. Some hints: 9w - w^3 : Factor out the w first. This leaves a difference of two squares. ...
January 24, 2009

college algebra
You're done. 9, 18, and 8 have no common factor other than 1. (9 = 3^2, 18 = 2*3^2, 8 = 2^3)
January 12, 2009

math
Remember, the diameter is twice the radius. (Equivalently, the radius is 1/2 the diameter)
December 21, 2008

To Everyone at Jiskha
Merry Christmas, Happy Hanukkah, Happy New Year, um . . . Io Saturnalia?
December 18, 2008

math
Not if it's a function in x. Think about what the y-intercept is - it's the value of f(x) for x=0. You can't get two different values out of that.
December 9, 2008

Math
Remember that a^(-x) = 1/(a^x), as long as a isn't zero. So 10^(-4) = 1/(10^4) = something you should be able to figure out.
December 8, 2008

pre cal
For the first one, remember that (a^b)^c = a^(bc). 2/3 * 3/2 = 1, so raise each side to the power of 3/2. That's all you need to do; you'll be left with x=(something). For the second, start by splitting the left side into two fractions, like so: (2^x)/(2^x) + 4/(2^x...
December 7, 2008

Algebra
This is a quadratic, so we'll try to factor it into (x+a)(x+b). The constant term is positive, so we know that a and b have the same sign. The x term is negative, so we know a and b are both negative. We need to find two negative numbers, a and b, such that a*b = 35 and a+...
December 7, 2008

math B
There should be a way to solve it, but we can't help without the diagram. We need to know where all the points are in relation to each other.
November 17, 2008

math B
This can't be answered without the diagram that should be with it.
November 17, 2008

Math
What's 0.25% as a decimal? Once you know that, it's just multiplication. (Remember, 1% = 0.01)
November 15, 2008

physics
Can you give an example of a problem you can't figure out? It'll be much easier to help with a specific example of the kind of thing you're having trouble with.
November 15, 2008

English
Both are grammatically correct (assuming you mean twenty-nine). There are guidelines some people like to follow for when to use the digits and when to write it out, but you should be fine using whichever seems to work best.
November 14, 2008

math
x^3 and 1x^3 are the same thing. The coefficient is just usually left off when it's a 1. As for the second problem, your answer isn't quite right. Recheck your x^3 and x terms; there should also be no constant term.
November 14, 2008

physics
Use Newton's law of gravitation. g=(m_1)(m_2)(G)/(d^2) m_1 = mass of first body m_2 = mass of second body G = gravitational constant (value is unimportant for this particular problem) d = distance between bodies.
November 14, 2008

Intro to Computer Programming - Pseudocode
You don't need a 2D array. You probably do need a loop (although some languages have features that kind of let you avoid that). You'll need at least two 1D arrays. (Possibly 3, depending on how you implement it) What you need to do is this: Get the student's ...
November 3, 2008

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