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Math Help - Finding the rectangle of greatest area...

  1. #1
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    Finding the rectangle of greatest area...

    A rectangle is to be drawn in the first quadrant with one leg on the y-axis, and the other on the x-axis, and a vertex on the curve y = 1-.22x^2 Find the coordinates of that vertex which form the rectangle of greatest area.
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    Quote Originally Posted by derekjonathon View Post
    A rectangle is to be drawn in the first quadrant with one leg on the y-axis, and the other on the x-axis, and a vertex on the curve y = 1-.22x^2 Find the coordinates of that vertex which form the rectangle of greatest area.
    A = xy = x(1-.22x^2)

    find \frac{dA}{dx} and maximize
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  3. #3
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    what do you mean find DA/dx?

    do you mean just find the derivative of x(1-.22x^2)?

    wouldn't that be (1-.22x^2)*-.44x?
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    Quote Originally Posted by derekjonathon View Post
    do you mean just find the derivative of x(1-.22x^2)?

    wouldn't that be (1-.22x^2)*-.44x?
    no ...

    A = x(1 - .22x^2)<br />

    distribute the x ...

    A = x - .22x^3

    now find the derivative, set it equal to 0, and solve for the value of x that maximizes A.
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