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Math Help - Combining Functions Homework Help

  1. #1
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    Post Combining Functions Homework Help

    The number of kidney and liver transplants in the United States between 1992 and 1996 can be modeled by

    K(x) = 9088.859 + 1697.717 In x kidney transplants
    L(x) = 2424.764 + 915.025 In x liver transplants

    where x is the number of years since 1990.

    a. Construct a model for the number of kidney and liver transplants between 1992 and 1996.

    b. Use the model to estimate the number of kidney and liver transplants in 1995.

    I have answers in the back of my book. I get the first answer. But I don't understand how to get the second.

    Answers

    a. T(x) = 9088.859 + 1697.717 In x + 2424.764 + 915.025 In x = 11,513.623 + 2612.742 In x kidney and liver transplants, where x is the number of years since 1990.

    b. T(5) = 15,719 approximately

    I don't not understand how to get the answer for b part, I can not get that answer I have tried many different ways to plug it in, and can not seem to get it. Please help.
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  2. #2
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    Quote Originally Posted by JBondman871 View Post
    The number of kidney and liver transplants in the United States between 1992 and 1996 can be modeled by

    K(x) = 9088.859 + 1697.717 In x kidney transplants
    L(x) = 2424.764 + 915.025 In x liver transplants

    where x is the number of years since 1990.

    a. Construct a model for the number of kidney and liver transplants between 1992 and 1996.

    b. Use the model to estimate the number of kidney and liver transplants in 1995.

    I have answers in the back of my book. I get the first answer. But I don't understand how to get the second.

    Answers

    a. T(x) = 9088.859 + 1697.717 In x + 2424.764 + 915.025 In x = 11,513.623 + 2612.742 In x kidney and liver transplants, where x is the number of years since 1990.

    b. T(5) = 15,719 approximately

    I don't not understand how to get the answer for b part, I can not get that answer I have tried many different ways to plug it in, and can not seem to get it. Please help.
    Substitute x = 5 into the rule from a. If you're doing that, then you are not entering the numbers into your calculator correctly. Make sure you're using the ln button, NOT the log button.
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  3. #3
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    Quote Originally Posted by JBondman871 View Post
    I have a TI 83 Plus what and where is the In button?
    What do you understand In x to mean in the formulae you're meant to be using?

    The button you should be using probably looks like LN. What button were you using to do the calculation?
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