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kdarnell08 Group Title

4x^2+81-36x

  • one year ago
  • one year ago

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  1. tkcena75 Group Title
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    (2x-9)^2

    • one year ago
  2. kdarnell08 Group Title
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    can ya go through the steps for me?

    • one year ago
  3. tcarroll010 Group Title
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    There are a couple of ways to do this. The quickest is factoring, if you are good at seeing factors. This is a little tricky with factoring, so when in doubt you can always use the quadratic formula (the second way) which is actually my favorite way.\[x = \frac{ -b \pm \sqrt{b ^{2} - 4ac} }{ 2a }\]where you have an equation in the form: ax^2 + bx + c = 0 So you have a=4, b=-36, and c=81 So, you substitute those into the formula.

    • one year ago
  4. kdarnell08 Group Title
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    ughh i just dont understand this!!

    • one year ago
  5. tcarroll010 Group Title
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    Well, let's look at factoring for a bit instead. As for factoring (the other way), you can rewrite the equation into: (2x)^2 - 36x + 9^2 You will see that the first term is a square and the third term is a square which might sugeest that the factors are squared.

    • one year ago
  6. tcarroll010 Group Title
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    That means that we can partially set up the solution: (2x )(2x ) But the third term is a square also, so going a bit further and just leaving out the signs: (2x 9)(2x 9) Now this all presupposes you can work the distributive law well enough: (a + b)(c + d) = a(c + d) + b(c + d) = ac + ad + bc + bd Tell me before we go any further, can you deal with that last equation?

    • one year ago
  7. kdarnell08 Group Title
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    yes.

    • one year ago
  8. tcarroll010 Group Title
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    That's great! That really is. Don't worry if it's a little rocky. You're not supposed to "see it all" right away, so we'll just go along until it gets murky for you. np. So, continuing where we left off with the factoring, writing it again: (2x 9)(2x 9) We have a good start, but we don't have signs yet. We know that 81 is positive so the signs are both negative or both positive. Since the 36x has a negative sign, we go with negative signs: (2x - 9)(2x - 9)

    • one year ago
  9. tcarroll010 Group Title
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    Now, we are goingto multiply this out to check our work: (2x)(2x - 9) - 9(2x - 9) = 4x^2 - 18x - 18x + 81 = 4x^2 - 36x + 81

    • one year ago
  10. tcarroll010 Group Title
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    So, that's the same as our original expression with a slight change in order of the terms. So, that's 2 ways to do this. Ok, your turn, ask questions.

    • one year ago
  11. kdarnell08 Group Title
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    ok. i understand most of it i just dont understand what happened to the #36

    • one year ago
  12. tcarroll010 Group Title
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    In the checking of the solution that I did, the -36x came from the -18x -18x

    • one year ago
  13. kdarnell08 Group Title
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    i get it!!!!!

    • one year ago
  14. tcarroll010 Group Title
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    Believe me. If really get this or most of it, or even half. That's real progress! For anyone! I suggest going over this a couple times to consolidate your understanding

    • one year ago
  15. tcarroll010 Group Title
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    And don't give up on the quadratic formula because that is actually much more important.

    • one year ago
  16. kdarnell08 Group Title
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    ok i already copied and pasted it to a word document. and ive used the equations for more than one of the other problems i have!

    • one year ago
  17. tcarroll010 Group Title
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    You very nice to work with because you really want to learn (all students should be that way) and you are a nice person.

    • one year ago
  18. kdarnell08 Group Title
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    thank you! i appreciate that. maybe its because they are mostly in high school. im in nursing school and am relearning everything and harly remember it all. i personallt DO NOT want to have to repay for this class. hs was 5 years ago so its a little more than rocky.

    • one year ago
  19. kdarnell08 Group Title
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    and its an online class. which is way harder than on campus

    • one year ago
  20. tcarroll010 Group Title
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    This is good what you just said. You are approaching this from a perspective that is more mature than high school. And the world needs good nurses. My sister is a nurse. She was also a math whiz, so she breezed through math. But just get through math since you already have a higher goal. And good luck in both math but especially the nursing!

    • one year ago
  21. kdarnell08 Group Title
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    thank you!

    • one year ago
  22. tcarroll010 Group Title
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    You are entirely welcome!

    • one year ago
  23. kdarnell08 Group Title
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    did i mention i hate rational expressions :)

    • one year ago
  24. tcarroll010 Group Title
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    lol then go with the irrational ones :-)

    • one year ago
  25. tcarroll010 Group Title
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    A little math humor. There's so little material from which to get humor in math!

    • one year ago
  26. kdarnell08 Group Title
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    haha. oh i am aware!

    • one year ago
  27. tcarroll010 Group Title
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    I think the developers of all these math formulas are secretly laughing in their graves at all the misery they caused!

    • one year ago
  28. tcarroll010 Group Title
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    I know! Maybe one day you can get a math PhD. as a patient! Payback!

    • one year ago
  29. kdarnell08 Group Title
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    hahahahaha. thats funny!!! i wouldnt doubt it!! all i know is this is the only subject that i curl up in the fetal position and cry over ;)

    • one year ago
  30. tcarroll010 Group Title
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    Math is tough because it is so unforgiving and as a field of study, it is so vertical. Can't go too far ahead without getting the basics.

    • one year ago
  31. kdarnell08 Group Title
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    uh oh. got to another one....wanna help?

    • one year ago
  32. tcarroll010 Group Title
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    vertical as in concepts building upon one another. Sure, I've got time for one more. Then I curl up and cry.

    • one year ago
  33. kdarnell08 Group Title
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    \[\frac{ x ^{2}-25 }{ x+5 }\]

    • one year ago
  34. tcarroll010 Group Title
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    Oh, you'll like this one because it's easier than the other one.

    • one year ago
  35. kdarnell08 Group Title
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    oh god i hope so lol

    • one year ago
  36. kdarnell08 Group Title
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    dont you get rid of the division and turn it to multipication

    • one year ago
  37. tcarroll010 Group Title
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    Sort of. I'm going to factor the numerator:\[\frac{ (x + 5) \times (x - 5) }{ (x + 5) }\]Now, the division concept comes into play insofar as the x + 5 factor cancels out of the numerator and the denominator and you are left with: x - 5 as your answer.

    • one year ago
  38. kdarnell08 Group Title
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    that i comletely understand!

    • one year ago
  39. tcarroll010 Group Title
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    Either the website or my computer just went goofy.

    • one year ago
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