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Calculus-Area between curves

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Sketch the region enclosed by the given curves. Decide whether to integrate with respect to x or y. Then find the area of the region.
2y=4*sqrt(x) , y=5 and 2y+4x=8

please help! i've been trying this problem the last couple days, even asked a TA for help, but i can't arrive at the right area between the curves. Thanks in advance!

  • Calculus-Area between curves -

    first of all reduce the equation to simplest form:
    y = 2√x
    y = 5
    y + 2x = 4

    Your sketch should look like a "triangle" with one side slightly curved
    see:
    http://www.wolframalpha.com/input/?i=plot+y%3D2*sqrt%28x%29+%2C+y%3D5+%2C+y%2B2x%3D4

    we need all the intersection points,
    I assume you know how to do that, ....
    but I will do the hardest one:
    intersect y = 2√x and y + 2x = 4
    then 2√x = (4-2x)
    or
    √x = 2-x
    by inspection, x = 1 , then in the originals , y = 2
    point of intersection is (1,2)
    Hoping that you get (-1/2, 5) and ( 25/4,5) for the other points

    so area
    = ∫(5 - (4-2x)) dx from -1/2 to 1 + ∫(5 - 2x^(1/2) dx from 1 to 25/4
    = (x + x^2)| from -1/2 to 1 + (5x - 4x^(-1/2) )| from 1 to 25/4
    = 1 + 1 - (-1/2 + 1/4) + (125/4 - 8/5 - (5-4) )
    = 2 + 1/4 + 125/4 - 8/5 - 1
    = 309/10

    you better check my arithmetic on that one, should have written it out on paper first.

  • Calculus-Area between curves -

    Thanks I figured it out my answer was 9, and it was correct

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