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Homework Help: Urgent Help Please

  1. Jun 29, 2006 #1
    hey Guys, im having a bit of trouble working out some questions i need to how to work out by tomorrow. I feel stupid for not thinking of this earlier but i have been flat out with study.

    can you help me work out these questions and show me how its done.

    Solve for X in the quations.

    1) 2^4x = 16
    2) ln(2x-5) = 1.9
    3) logbase7(x) = 5

    4) the intensity I of light passing through a window, measured in lumens, is given by the formula

    I(d) = 52e^-4.5d

    (i) where d is the thickness (in centimeters) of glass in the window.
    find the intensity if the thickness is 2.2 cm

    (ii) find the thickness required to give an intensity of 12 lumens. give answer in centimeters to at least three decimal places.

    5) Explain why the quadratic equation x^2-6x+140=0 has no real solution for x.

    6) on dividing (x+2) into 2x^5-3x^2+x-1 there is both a quotient and remainder.

    Thus 2x^5-3x^2+x-1 = q(x)(x+2) + R

    where q(x) is a polynomial in x of degree 4, and R is a constant. Find R?


    Find all solutions to the system.

    x-2y+2z = -6
    3x-5y+6z = -15
    2x+4y-12z = 44

    8) write the equation 5x+3y = 4 in parametric form. That is express both x and y in terms of the same parameter

    9) solve x(2x-3)^2 = 4x^3+7x-60 for x

    Hope this isnt to much to ask. I will be so very thankfull to anybody who can help me.

    Thanx in advance

  2. jcsd
  3. Jun 29, 2006 #2


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    Staff Emeritus
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    Gold Member

    The rules with homework help are generally that you have to show some working before anybody atempts to help you. Frankly for being flat out with study you should easily get these questions.

    Anyway show a bit of working for each and I'm sure you'll receive loads of hints but we will not do your homework for you.
  4. Jun 29, 2006 #3


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    Must have taken more time to copy that from the homework sheet than to sit down and solve the problems o:)
  5. Jun 29, 2006 #4


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    Homework Helper

    No, this isn't too much at all. :)
    Yes, we are very willing to help you solve all those problem. But what I mean by help is that, if you are stuck somewhere in your work, we can help you; or we can point out where the errors in your work are; we can even help you start the problem in case you don't know how. However, we won't show COMPLETE solutions.
    You can take time to view some of the old rules here.

    Common, show your work, show us what you have done, and what you think, where you get stuck and we can help you. :)
    Ok, in case you don't know how to start all those problem. Say, can you find y in terms of x, if you know that x = logay? :)
    Last edited: Jun 29, 2006
  6. Jun 29, 2006 #5
    yer well they where the only ones out of about 500 i didnt no where to start. thanx for nothing.
  7. Jun 29, 2006 #6


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    Staff Emeritus
    Science Advisor
    Gold Member

    There are very good reasons why we do not do peoples homework for them.

    Firstly you learn nothing just being handed the answers and secondly its to stop people from getting credit for work they did not do themselves.

    I will hint at the answers to the first 3 questions.

    1.) y=b^x is equivalent to log_b(y) = x
    2.) take the exponential of both sides
    3.) same as 1.)
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