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Math Help - Using Function's Graph

  1. #1
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    Using Function's Graph

    There is a picture of a function's graph with a curve CONNECTING the following points on the xy-plane:

    (-6, 3), (-3, 0), (0, 3), (2, 4), (6, 0), (8, -2), (10, 0)
    and (11, 1).

    QUESTIONS: a - d.

    (a) Is f(8) positive or negative? Why? Why not?

    (b) For what numbers x is f(x) > 0?

    (c) What are the x-and y-intercepts, IF ANY?

    (d) How often does the line y = 1/2 intersect the graph?

    Thanks!
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  2. #2
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    Quote Originally Posted by symmetry View Post
    There is a picture of a function's graph with a curve CONNECTING the following points on the xy-plane:

    (-6, 3), (-3, 0), (0, 3), (2, 4), (6, 0), (8, -2), (10, 0)
    and (11, 1).

    QUESTIONS: a - d.

    (a) Is f(8) positive or negative? Why? Why not?

    (b) For what numbers x is f(x) > 0?

    (c) What are the x-and y-intercepts, IF ANY?

    (d) How often does the line y = 1/2 intersect the graph?

    Thanks!
    Hello symmetry,

    a.) f(8) is asking what the y value is at x = 8; we are given (8, -2), so at x = 8, y = -2. From this information, do you think f(8) is positive or negative? It should be self explanatory. In fact, on the interval from x = -6 to x = 11, the only time the graph is negative is between x = 6 and x = 10.

    b.) Nice, I practically answered this answer in a. Take all the other values and you have when f(x) > 0.

    c.) This question is asking when is x = 0 and when is y = 0. Just by looking at the graph and seeing when the graph goes through the x and y-axis, you should be able to answer this question. Or, just look at the points, and see when the x or y values are 0.

    d.) y = 1/2 is a horizontal line. Draw a horizontal line at y = 1/2.

    It will intersect the graph exactly 4 times.
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  3. #3
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    ok

    It's easier than I thought.

    Thanks!
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