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Thread: Easy stuff.

  1. #1
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    Default Easy stuff.

    So I have to do some work I haven't thought about in a while, and didn't listen to. Just some applications of systems of equations.

    Daniel and Matt are selling cookie dough for a school fundraiser. They're selling sugar cookie dough and oatmeal cookie dough. Daniel sold 12 packages of sugar dough and 8 packages of oatmeal dough for $196. Matt sold 13 packs of sugar dough and 4 packs of oatmeal dough for $161.

    Can someone just quickly show me how to set up the equation for this? I can solve it, I just forget that.

    *whistles* Now I feel kinda stupid .

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    s = # of sugar cookie packages sold
    o = # of oatmeal cookie packages sold

    Daniel:

    12s + 8o = 196

    Matt:

    13s + 4o = 161

    But here's more to the question than that, so you should include that.

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    What do you mean there's more? All that's left is the question itself (find the cost).

    Also, that's what I did and it didn't seem to work D:.

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    Because that's not a system of equations. It's a single inequality for two people. There's no more to do than that, other than guess and check.. Without more information, that is.

    Oh no wait. One sec.

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    Just saying what my teacher told me xP.

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    12s + 8o = 196

    (13s + 4o = 161) * -2

    ---

    12s + 8o = 196

    -26s + -8o = -322

    ---

    (-26s = -322) * -1 (just because it's easier, imo.)

    ---

    (26s)/26 = (322)/26

    ---

    s = 161/13

    ---

    12(161/13) + 8o = 196

    ---

    1932/13 + 8o = 196

    ---

    (1932/13) - (1932/13) + 8o = 196

    ---

    (1/8) * (8o) = (616/13) * (1/8)

    ---

    o = 77/13

    ---

    12(161/13) + 8(77/13) = 196

    ---

    (1932/13 + 616/13 = 196)13

    ---

    1932 + 616 = 2548

    ---

    2548 = 2548

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    S = 161/13 = $12.38
    O = 77/13 = $5.92

    That's all I needed. Thanks!

    Hey-o!

    In case you look at this again, I need some more help (again, on stuff I didn't listen to xD).

    I need to graph a compound inequality after solving it:

    49 < -6n + 1 <= -17

    I've been searching google, but they all talk about it differently D:.

    Edit again! I found it .
    Last edited by Sandstorm; 10-28-2010 at 02:15 AM.

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    So you don't need help with that inequality or do you?

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    Quote Originally Posted by i luffs yeww View Post
    So you don't need help with that inequality or do you?
    Just to make sure I did it right:


    49 < -6n + 1 <= -17

    49 < -6n + 1

    Reverse it, so it looks better:

    -6n + 1 > 49

    Remove one, to get -6n by itself.

    -6n > 48

    Divide by -6.

    n > -8

    One of the two answers is n > -8.

    -6n + 1 <= -17

    Remove one to get -6n by itself.

    -6n <= -18

    Divide by -6 to get N by itself.

    n <= -3

    N <= -3 and n > -8

    N is less than or equal to -3 and greater than -8.

    Graph it (can't do it here) - closed dot for n <= -3, open dot for n > -8.

    Check:

    49 < -6n + 1 <= -17

    Choose a number greater than -3, a number lower than -8, and a number that should match the equation.

    I'll use -2.

    -6(-2) + 1 = 13. Greater than 49? No. Less than -17? No. False.

    For the second, -9.

    -6(-9) + 1 = 55. Greater than 49? Yes. Less than -17? No. False.

    For the third, -5.

    -6(-5) + 1 = 31. Greater than 49? No. Less than -17? No. False.

    Therefore, the inequality is false, and my answer is false, plus the graph.

    I think I did that right. Knowing me I did it totally wrong.

    Edit:

    Looking at it, I realized that something can't be greater than 49 and less than -17 at the same time, saving me all the trouble of solving it. But I did it to make sure I understand it.
    Last edited by Sandstorm; 10-28-2010 at 03:04 AM.

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    Just plug things back in to check.

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