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Math Help - area between curve and x-axis

  1. #1
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    area between curve and x-axis

    Find the area bounded by the following:

     <br />
y=\frac{1}{\sqrt{3x+7}}  ;  x=-1, x=3,x-axis<br />
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  2. #2
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    Quote Originally Posted by Punch View Post
    Find the area bounded by the following:

     <br />
y=\frac{1}{\sqrt{3x+7}} ; x=-1, x=3,x-axis<br />
    \int_{-1}^{3}\frac{dx}{\sqrt{3x+7}}\,\, ;u=3x+7 \implies du=3dx \implies \frac{1}{4}\int_{4}^{16}u^{-\frac{1}{2}}du
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  3. #3
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    Correct me if I am wrong

    Quote Originally Posted by Punch View Post
    Find the area bounded by the following:

     <br />
y=\frac{1}{\sqrt{3x+7}}  ;  x=-1, x=3,x-axis<br />
    Correct me if I am wrong, but I believe the multiplier outside of the integral should be one third
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  4. #4
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    sorry emptyset.. but i dont understand the part where u wrote \int_{4}^{16}u^{-\frac{1}{2}}du

    isnt it suppose to be 3 on top and -1 below?
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  5. #5
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    Those are the limits for x, but you are now working with the variable u = 3x+7.

    Check out what the values of u are when x=-1 and x=3.
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