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Math Help - finding a number so that f is continuous at every point

  1. #1
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    finding a number so that f is continuous at every point

    Good evening everyone need some help with this problem i got wrong, have an exam tomorrow and i'm trying to figure this out. Thanks in advance!

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  2. #2
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    Quote Originally Posted by tecknics View Post
    Good evening everyone need some help with this problem i got wrong, have an exam tomorrow and i'm trying to figure this out. Thanks in advance!

    \lim_{x \to -5^-} f(x) = \lim_{x \to -5^+} f(x) = -12

    and

    \lim_{x \to 1^-} f(x) = \lim_{x \to 1^+} f(x) = 12

    you'll get two equations in terms of a and b ... solve the system.
    Last edited by skeeter; September 16th 2009 at 02:20 PM. Reason: fix x-values in 2nd limit
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  3. #3
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    Quote Originally Posted by skeeter View Post
    \lim_{x \to -5^-} f(x) = \lim_{x \to -5^+} f(x) = -12

    and

    \lim_{x \to -5^-} f(x) = \lim_{x \to -5^+} f(x) = 12

    you'll get two equations in terms of a and b ... solve the system.
    I know how to do that part you just showed, but as far as the next step im lost
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  4. #4
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    \lim_{x \to -5^-} -12 = \lim_{x \to -5^+} ax+b

    -12 = a(-5)+b



    \lim_{x \to 1^-} ax+b = \lim_{x \to 1^+} 12

    a+b = 12


    solve the system
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  5. #5
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    Quote Originally Posted by skeeter View Post
    \lim_{x \to -5^-} -12 = \lim_{x \to -5^+} ax+b

    -12 = a(-5)+b



    \lim_{x \to 1^-} ax+b = \lim_{x \to 1^+} 12

    a+b = 12


    solve the system
    That makes sense to me now, but now i'm lost for solving the system, i was in Iraq for a year and completely forgot about everything math related and need to practice some more.
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  6. #6
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    Wooo, i got it just now thank you very much!
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