MAT 180: The SandBox

Use this page to ask anything related to MAT 180. If you are registered and logged in, your posts will display your user name. If you would like to post anonymously, make sure you are logged out. Anyone is allowed to post.


91 thoughts on “MAT 180: The SandBox

  1. For Problem 11 on the WeBWorK I did the division correctly as my quotient was right, but my remainder was wrong. I got 14 as my remainder.

  2. For WeBWorK 10 Problem 2, how do I get the last root of the function off the graph? I have the first three, but I need one more given the function is a 4th degree.

    1. Assuming the graph has zeros \(x=1,-1,\) and \(0\), then the equation for the function should be of the following form:
      $$
      f(x) = k(x-1)(x+1)x
      $$
      where \(k\) is some constant to be determined. In addition, you have one other point \((2,-1)\) which the function must pass through. Therefore, substituting in this ordered pair into our equation, we obtain the value of \(k\):
      $$
      -1 = k(2-1)(2+1)2
      $$
      or that \(k = -1/6.\)

      So, the equation which has the given graph is given by
      $$
      f(x) = \frac{-1}{6} (x-1)(x+1)x.
      $$

    2. I got 8/63 as my value for k, but it was wrong. So I set the problem up like so: -8=k(1-8)(1+8)1. Simplifying this gives you -63k=-8. Divide by -63 and you get 8/63.

  3. Professor Nevo, for Problem 1 on WeBWorK 10 I’m getting x^4-4x^3-19x^2+46x-24 as my answer. It’s wrong, but I don’t know why. How do I account for the y intercept at (0,12)?

  4. This message comes up when I try to put in the answer for Problem 8 Set 9
    Warning — there may be something wrong with this question. Please inform your instructor including the warning messages below.
    WeBWorK error

    An error occured while processing your request. For help, please send mail to this site’s webmaster (webmaster@localhost), including all of the following information as well as what what you were doing when the error occured.

    Wed Jun 12 16:41:19 2013
    Warning messages

    Processing of this PG problem was not completed. Probably because of a syntax error. The translator died prematurely and no PG warning messages were transmitted. at /opt/webwork/webwork2/lib/WeBWorK/ContentGenerator/Problem.pm line 752.

    Error messages

    Can’t use an undefined value as an ARRAY reference at /opt/webwork/webwork2/lib/WeBWorK/ContentGenerator/Problem.pm line 215.

    Call stack

    The information below can help locate the source of the problem.

    in WeBWorK::ContentGenerator::Problem::attemptResults called at line 1400 of /opt/webwork/webwork2/lib/WeBWorK/ContentGenerator/Problem.pm
    in WeBWorK::ContentGenerator::Problem::output_summary called at line 152 of /opt/webwork/webwork2/lib/WeBWorK/Template.pm
    in WeBWorK::Template::template called at line 496 of /opt/webwork/webwork2/lib/WeBWorK/ContentGenerator.pm
    in WeBWorK::ContentGenerator::content called at line 477 of /opt/webwork/webwork2/lib/WeBWorK/ContentGenerator/Problem.pm
    in WeBWorK::ContentGenerator::Problem::content called at line 200 of /opt/webwork/webwork2/lib/WeBWorK/ContentGenerator.pm
    in WeBWorK::ContentGenerator::go called at line 371 of /opt/webwork/webwork2/lib/WeBWorK.pm

    Request information
    Method POST
    URI /webwork2/BCC-MAT-180/WeBWorK_9/8/
    HTTP Headers
    User-Agent Mozilla/5.0 (Windows NT 6.1; WOW64; rv:11.0) Gecko/20100101 Firefox/11.0
    Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    Connection keep-alive
    Referer http://wwserver.aorinevo.com/webwork2/BCC-MAT-180/WeBWorK_9/8/?user=bccfgryglak599170&effectiveUser=bccfgryglak599170&key=dA1Lq0R5dgc4bzdn3mz6iYczvFd9a5lY&theme=&displayMode=images&showOldAnswers=1
    Content-Length 1598
    Accept-Encoding gzip, deflate
    Content-Type multipart/form-data; boundary=—————————23655155744031
    Accept-Language en-us,en;q=0.5
    Cookie WeBWorKCourseAuthen.BCC-MAT-180=bccfgryglak599170%09dA1Lq0R5dgc4bzdn3mz6iYczvFd9a5lY%091371069669; __qca=P0-335297657-1370548257134
    Host wwserver.aorinevo.com

  5. For Problem 8 on WeBWorK how would I find the other two numbers where the company breaks even? I have the first one.

    1. Break-even occurs when revenue equals cost or, equivalently, when profit equals zero. That is, if P(x) is the profit function, then break-even is a solution to P(x) = 0.

  6. Professor Nevo, for Problems 12 & 13, I’m not sure how to input my answers. I have a list of x values, but the problem is asking for an inequality. Why is this?

    1. Here is an example: Suppose you want to find two different polynomials that have zeros \(x = 0\) and \(x = -2\). Then certainly \(f(x) = x(x+2)\) and \(g(x) = 3x(x+2)\) satisfy the given conditions.

  7. For WebWork9 I don’t understand why the answers of problems 12 and 13 have to be inequalities? The final factored forms are \(3x^2(x+4)(x-4)\) and \(4x(x+4)(x-3)\) respectively leaving the roots to be 0,4,-4 and 0,-4,3, I believe; how do I enter this as an inequality?

    1. WeBWorK wants the input to be in the form “x = 0 or x = 4 or x = -4” in whatever order you like. The main thing is to list the solutions as “x = a”, where “a” is a solution, separated by “or”.

Leave a Reply

Your email address will not be published. Required fields are marked *