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Math Help - Need some help with part A

  1. #1
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    Need some help with part A

    2. Let P=(x, y) be a point on the graph of y = x^2 - 8.
    a) Express the distance of d from P to the point (0, -1) as a function of x.
    b) What is d if x = 0?
    c) What is d if x = -1?
    d) Use a graphing utility to graph d = d (x).
    e) For what values of x is d smallest?

    Answers
    a) d(x) = √x^4-13x^2+49
    b) d(0)=7
    c) d(-1)= √37 ... is similar to ... 6.08
    d) Graph d(x) = √x^4-13x^2+49
    e) D is the smallest when x ... is similar to ... -2.55 or x ... is similar to ... 2.55


    I can do all of them but part A can someone help me figure out how to find out part A?

    and how do you do a "... is similar to ..." sign on here?
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  2. #2
    hpe
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    Quote Originally Posted by Robthebear
    2. Let P=(x, y) be a point on the graph of y = x^2 - 8.
    a) Express the distance of d from P to the point (0, -1) as a function of x.
    [...]
    I can do all of them but part A can someone help me figure out how to find out part A?

    and how do you do a "... is similar to ..." sign on here?
     \sim or \approx or simply ~.

    As to part a: The distance between points with coordinates (a,b) and (c,d) is
     \sqrt{(a-c)^2 + (b-d)^2}.
    Now in this case, a = x, b = y = x^2-8, \, c = 0,\, d = -1.
    Insert these expressions in the distance formula and you are done.
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  3. #3
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    Thank you for the help.
    Robert
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