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Thread: Linear Equations +fullrep

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    Maki's Avatar
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    Linear Equations +fullrep

    Find the value of k that makes the following function continuous. Justify your answer.

    f(x) = { x +3 if x < 1
    -2x + k if x >/= 1

    Graham's long-distance telephone plan includes the first 500 minutes per month in the $15.00 charge. For each minute after 500 minutes, Graham is charged $0.02. Write a function that describes Graham's total long-distance charge in terms of the number of long distance minutes he uses in a month.

    +FULLrep for a process + explanation please =( Fuk dis shiz
    Last edited by Maki; 02-08-2014 at 12:49 AM.

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    Quote Originally Posted by Mint View Post
    At 9:20 am, Adrian left Windsor with 64L of gas in his car. He drove east at 100 km/h. The low fuel warning light came on when 10 L of gas were left. Adrian's car uses gas at the rate of 8.8L/100km. When did the warning light come on?

    +FULL(5)rep for a detained explanation as to how you get your answer, which should be 6h 8m after 9:20 am (3:28 pm) Help wanted pleaseeeeeeee >_<
    Okay so Adrian started with 64 L in his gas tank and the light came on when he had 10 L left, so he used 54 L in that time. If he is going 100 km/h, he uses 8.8 L every 100 km he travels. So you need to divide 54 by 8.8 and you get 6.13, or 6 hours and .13 of an hour (which just happens to be 8 minutes) If he left at 9:20, you add the 6 hours and 13 minutes to the time until you get your answer of 3:28 PM

    As for #2, that' a bit more tricky. You should first start with the total amount in each category (25k, 35k etc) and choose the highest number in that range. So in this case, lets use 35k. Now if she sells 35k worth of stuff, she gets 5.5% sales. Now you multiply 35000 by .055 to get her commission of $1925. You should do this for all of them (25k * .05, 35k * .055, 45k * .06, and 50k * .07) Now that you've found all those numbers, look for the range where $2000 would fall in (the 6% on 35k-45k) Now that you know the percent, you divide 2000 by .06 to get your answer

    Edit: Actually #2 doesnt quite equal 38333, it only equals $33333 so blah
    Last edited by Andymac106; 02-06-2014 at 05:32 PM.

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    Quote Originally Posted by Andymac106 View Post
    Okay so Adrian started with 64 L in his gas tank and the light came on when he had 10 L left, so he used 54 L in that time. If he is going 100 km/h, he uses 8.8 L every 100 km he travels. So you need to divide 54 by 8.8 and you get 6.13, or 6 hours and .13 of an hour (which just happens to be 8 minutes) If he left at 9:20, you add the 6 hours and 13 minutes to the time until you get your answer of 3:28 PM
    Quote Originally Posted by Andymac106 View Post
    Okay so Adrian started with 64 L in his gas tank and the light came on when he had 10 L left, so he used 54 L in that time. If he is going 100 km/h, he uses 8.8 L every 100 km he travels. So you need to divide 54 by 8.8 and you get 6.13, or 6 hours and .13 of an hour (which just happens to be 8 minutes) If he left at 9:20, you add the 6 hours and 13 minutes to the time until you get your answer of 3:28 PM
    The textbook process says something a LOT more complicated =___=

    G=64-8.8t,
    where G = amount of gas (L) and t = time (hours)

    10 = 64 - 8.8t
    10 - 10 = 64 - 8.8t - 10
    0 = 54 - 8.8t
    8.8t = 54
    t = 54/8.8
    t = 6.14


    0.14 x 60 = 8.4

    The warning light came on about 6h 8m after 9:20 am, which is about 3:28 pm

    ------------

    Could you explain this process to me? I dont really get it, your explanation makes more sense, but I have a feeling the above process is really important D:
    Like, if G is the amount of gas in litres, why is it 10 and not 64???

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    Quote Originally Posted by Mint View Post
    The textbook process says something a LOT more complicated =___=

    G=64-8.8t,
    where G = amount of gas (L) and t = time (hours)

    10 = 64 - 8.8t
    10 - 10 = 64 - 8.8t - 10
    0 = 54 - 8.8t
    8.8t = 54
    t = 54/8.8
    t = 6.14


    0.14 x 60 = 8.4

    The warning light came on about 6h 8m after 9:20 am, which is about 3:28 pm

    ------------

    Could you explain this process to me? I dont really get it, your explanation makes more sense, but I have a feeling the above process is really important D:
    Like, if G is the amount of gas in litres, why is it 10 and not 64???
    What your text book said is exactly what I said, just put in a prettier equation

    G is 10 because that's how much gas there was when the light came on. You're looking for when the light came on now when you originally started. So you have 10 = 64-8.8t which is showing that (64-8.8t) must equal 10. Now the next step is to subtract 10, which IMO, is useless. Because you are trying to isolate your variable so why not just subtract 64 from the right side?? But the key is to end up with 54 = 8.8t (or if you used my method, -54 = -8.8t, whichever way you decide to isolate the variable) now you must divide everything by 8.8. (or -8.8 but I'm sure you're keeping up with that ) You end up with t = 6.14. The 6 represents the whole number of hours. You multiply .14 by 60 to get 8.4 to find the number of minutes. Did that help?

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    Maki (02-06-2014)

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    Updated with new problems sigh
    Last edited by Maki; 02-08-2014 at 12:43 AM.

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    f(x) = {im gonna kms

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    Raj (02-08-2014)

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    Are those 2 up there separate problems or just 1 problem?

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    Quote Originally Posted by Andymac106 View Post
    Are those 2 up there separate problems or just 1 problem?

    They're separate, my bad

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    Mint bless your soul.
    I hated this in high school.

    I DID MY TIME, TWELVE YEARS OF IT. IN AZKABAN.

    Why, yes. The world does revolve around me.
    (you need an account to see links)
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    Quote Originally Posted by Mint View Post
    Find the value of k that makes the following function continuous. Justify your answer.

    f(x) = { x +3 if x < 1
    -2x + k if x >/= 1

    Graham's long-distance telephone plan includes the first 500 minutes per month in the $15.00 charge. For each minute after 500 minutes, Graham is charged $0.02. Write a function that describes Graham's total long-distance charge in terms of the number of long distance minutes he uses in a month.

    +FULLrep for a process + explanation please =( Fuk dis shiz
    #2, since it looks easier So you have a constant value of $15 every month. Then you have .02x when x > 500 where x is the number of minutes that he talks. Now I believe that you would write it like this: C (cost) = .02x + 15 if x > 500. C = 15 if x < 500. Does that make sense? Now I'm pretty positive thats how you write it, just not 100% like I have been on all the rest that I've helped you with..

    #1: I'll have to think about this one but I'll get back to you

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