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Math Help - Functions of their graphs

  1. #1
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    Functions of their graphs

    F(x)= (x^2 + 2)/ (x + 4)

    a) What is the domain of f?
    b)List the x-intercepts, if any, of the graph of f.
    c)List the y-intercept, if there is one, of the graph of f.

    Thank you!
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  2. #2
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    (a) What x values can the function not have? Hint: Denominator = 0?

    (b)To find the x-intercept, notice that the y-coordinate will be equal to 0. So set f(x) = 0 and solve for x, i.e.:
    0 = \frac{x^{2} + 2}{x+4} (Can you even solve this? If not, what does that mean?)

    (c) To find the y-intercept, notice that the x-coordinate will be equal to 0. So replace each x with a 0 and solve for f(0).
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  3. #3
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    a) -4
    b) x-intercept = 0
    c) y-intercept = 1/2

    Are these values correct?
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  4. #4
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    Just to reiterate, what you got for (a) is the value you cannot have in your domain.

    All is correct except for (b).

    Remember that whatever you x-intercept is, it will have a y-coordinate of 0. If you plug in x = 0 into f(x), do you get 0?
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  5. #5
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    B) would the answer be undefined?

    Thanks.
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  6. #6
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    Not undefined. Just that it doesn't exist! Since you can't find a solution, it means your graph doesn't have a x-intercept.
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