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Homework Help: Simplification and solving of equation

  1. Jul 30, 2012 #1
    1. The problem statement, all variables and given/known data
    The problem are two:
    (1) Simplify: 1/4(2n- 2n+2)

    (2) Solve the equation 2(2x+1)- 9(2x) + 4 = 0
    2. Relevant equations

    3. The attempt at a solution
    for the number one question, simplify:
    1/4(2n- 2n+2)

    1/4(2n- 2n+2)
    = 4-1(2n-2n+2)
    = 2(-2)(2n-2n+2)
    = 2(-2)(2n-2n*22
    I can't go further please I need asistance.

    For the second question, solve the equation:
    2(2x+1)- 9(2x) + 4 = 0

    I don't just know how to start dealing with the question. It is really a troubsome question.
    Last edited: Jul 30, 2012
  2. jcsd
  3. Jul 30, 2012 #2
    I'm confused as to your original equations.

    $$(2)\ 2^{2x+1} - 9(2^x + 4)$$

    Are those correct?
  4. Jul 30, 2012 #3

    Ray Vickson

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    Use [S U P] and [/S U P] (but with no spaces), not [sup ] and [ /sup]. In fact, just use the "X[SUP]2[/SUP]" button on the palette at the top in the input panel.

    Last edited: Jul 30, 2012
  5. Jul 30, 2012 #4
    I have edited the problem so that it can be seen clearly.
  6. Jul 30, 2012 #5
    I have edited my opening post so that it can be seen clearly. Maybe you can look at the problem again.
  7. Jul 30, 2012 #6
    For (1), you are close. Combine like terms.

    For (2), it is actually a quadratic. Can you see what the variable is?
  8. Jul 30, 2012 #7
    If like terms is collected, the expression will look like this:
    = 2(2n-2n)
    = 2n+1-2n

    No! I didn't see the variable.
  9. Jul 30, 2012 #8


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    This does not follow from the last line you had written in your opening post:
    What we have so far is

    [tex]2^{-2}(2^n-2^n\cdot 2^2)[/tex]

    Can you expand this?

    There is a basic rule of exponentiation that says that if you exponentiate an exponent, you multiply the exponents together. What this is saying is that

    So then what does [itex](2^x)^2[/itex] simplify to?
  10. Jul 30, 2012 #9


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    Nope. Look at the last step in your original post:
    Answer this: what is x - 4x?
    Now answer this: what is 2n - 4*2n?
    That's what Villyer meant by combining terms.

    [itex]2^{2x+1} - 9\cdot 2^x + 4[/itex]
    Rewrite the 1st term so it looks like (something) times 22x.

    EDIT: Beaten to it. :wink:
  11. Jul 30, 2012 #10
    I don't understand what you guys are writing, write using the same format I used in showing my raise to power in my opening post. I will understand it better and therefore be able to respond to the numerous replies you guys are posting.
  12. Jul 30, 2012 #11


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    You can't see Latex? I think you should try find out and fix what the problem is on your end, because Latex is commonly used on this forum and not just in this thread.
  13. Jul 30, 2012 #12
    Please help me, I belive I would be able to understand and write using latex with time. Please help me, I really need this help please!
  14. Jul 30, 2012 #13


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    I'm not asking you to learn to use latex so suddenly, but rather I'm confused as to why you can't read what we've written. Correct me if I'm wrong, but I think that Latex is software that's inbuilt into this forum, so basically everyone can read it (unless they have some horribly outdated internet browser).

    Anyway, I'll edit what emuyang and I wrote in the format you've requested.

    EDIT: Changed the ^ to [sup ] tags
    Last edited: Jul 30, 2012
  15. Jul 30, 2012 #14

    Ray Vickson

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    You have been given lots of help---any more help and we would be doing your homework for you. If you are having trouble understanding what people write you need to sit down with a pencil and several sheets of paper and start writing things down in whatever notation you like.

  16. Jul 30, 2012 #15
    I did not ask you to do my home work. What I ask is this: give me directions that will help me do the homework. That's all that I ask, anything far from that then you are doing my homework. I know that you are giving me some asistance, but how can I work with the language I don't understand. I know that apart from latex, there are other formats that can be used and I will be able to understand all the replies you are posting and be able to respond accordingly.
  17. Jul 30, 2012 #16

    Ray Vickson

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    Here is what one responder said to you:

    "Answer this: what is x - 4x?
    Now answer this: what is 2n - 4*2n? "

    So, what are your answers? Do you see why the answers are important?

    Last edited: Jul 30, 2012
  18. Jul 30, 2012 #17
    Is just an expression an algebraic expression. If factored it will look like this: x(1-4)
    = x(1-2)(2+1)
    That is 2 raise power n minus 4 times 2 raise to power n. It can be simplified further to appear like this: 2n - 22 * 2n
    = 2n/22+n
    = 2n-(2+n)
    = 2n-2-n
  19. Jul 30, 2012 #18


    Staff: Mentor

    But neither of these is the simplest way to write it. It's not very useful to factor 1 - 4.
    The above is not wrong, but it's not helpful to write 4 as 22.
    Your work below here is incorrect.
    These two problems are similar, and you are making them much more complicated than they deserve.
  20. Jul 30, 2012 #19
    What else can I do then?
  21. Jul 30, 2012 #20


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    1 - 4 = -3, Correct ?
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