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  1. #1
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    Red face expression

    I need to write this as an algebraic expression: During a drought a reservoir drops 3 in. ea. week for x straight weeks. Express the overall change in water level as an algebraic expression... Please and thank you!
    I thought it would be -3n or -3(N) BUT MY PROF. TOOK HALF A POINT AWAY!
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by thisflyispissinmeoff View Post
    I need to write this as an algebraic expression: During a drought a reservoir drops 3 in. ea. week for x straight weeks. Express the overall change in water level as an algebraic expression... Please and thank you!
    I thought it would be -3n or -3(N) BUT MY PROF. TOOK HALF A POINT AWAY!
    what is N?

    you can't just state some variable and not say what it is

    Let N_0 be the original level of the water before the drought.

    Then, after x weeks, the level of the water will be N_0 - 3x
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  3. #3
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    Red face

    Quote Originally Posted by Jhevon View Post
    what is N?

    you can't just state some variable and not say what it is

    Let N_0 be the original level of the water before the drought.

    Then, after x weeks, the level of the water will be N_0 - 3x
    i KNOW! tHIS WAS HIS EXACT QUESTION word FOR word stupid caps-sorry - I'm tired! I don't understand it at all, you need at least 1 more variable, right?
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  4. #4
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    Quote Originally Posted by Jhevon View Post
    what is N?

    you can't just state some variable and not say what it is

    Let N_0 be the original level of the water before the drought.

    Then, after x weeks, the level of the water will be N_0 - 3x
    would it be (n-3)x ? u think? Thanks, by the way, for yor response!
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  5. #5
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by thisflyispissinmeoff View Post
    i KNOW! tHIS WAS HIS EXACT QUESTION word FOR word stupid caps-sorry - I'm tired! I don't understand it at all, you need at least 1 more variable, right?
    well, it depends on how you want the answer to be expressed.

    if you want to know the level of water after x weeks, then it is (N - 3x)

    if you want to know by how many inches the water level dropped after x weeks, then it is 3x
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  6. #6
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    Quote Originally Posted by Jhevon View Post
    well, it depends on how you want the answer to be expressed.

    if you want to know the level of water after x weeks, then it is (N - 3x)

    if you want to know by how many inches the water level dropped after x weeks, then it is 3x
    just 3x? what about the variable n? He wants "to express the overall change in water level 9AFTER 3 WKS) AS AN ALGEBRAIC EQUATION.
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  7. #7
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by thisflyispissinmeoff View Post
    just 3x? what about the variable n? He wants "to express the overall change in water level 9AFTER 3 WKS) AS AN ALGEBRAIC EQUATION.
    ok, then it's just 3x, if you want an equation:

    Let C be the change in the water level after x weeks

    then, C = 3x

    so after, say, 3 weeks, the change in the water level is 9 inches, since the water level will drop 9 inches over this period of time, which is what plugging in 3 into our formula yields
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