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Homework Help: What is the domain and range of y=-0.7x+1.9 and y=0.7x+1.9?

  1. Mar 24, 2012 #1
    1. The problem statement, all variables and given/known data
    State the domain and range of the function that models each half of the roof (triangle)

    2. Relevant equations
    Y= -0.7x+1.9 (left half)
    Y= 0.7x+1.9 (right half)

    3. The attempt at a solution

    Why is the answer:

    Left half: domain: −2.7≤x≤0 range: 0≤y≤1.9
    Right half: Domain: 0≤x≤2.7 range: 0≤y≤1.9

    I don't understand.
  2. jcsd
  3. Mar 24, 2012 #2
    Haven't you tried graphing this on your calculator?
  4. Mar 24, 2012 #3
    yes I did, and I don't get how for the domain -2.7 is less than or equal to x less than or equal to 0?
  5. Mar 24, 2012 #4
    If it's modelling a triangle, then draw a picture.

    You'll see that the maximum value of the range is 1.9 (the intersection of the two lines) and the minimum is 0 (because a side of a triangle can't be negative).

    Then solve the equations for y=0 and y=1.9 to get the values of the Domains.
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