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Thread: maxima minima help

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    maxima minima help

    heey guys how would I do these
    1. The revenue from a company's product is given by R=180m+42m^2-m^3 where m is the output (per unit of time). Determine the output that will give maximum revenue.

    2. An objet is projected into the air. The height of the object after t seconds is given by h=60t-5t^2
    (I) what is the maximum height the object reaches?
    (ii) how long after reaching the maximum height is the object 100m above its starting level?

    for 2i I got 180m? is it right? dunno the rest

    thank you all!

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    Senior Member integral95's Avatar
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    Re: maxima minima help

    1. you find dR/dm (differentiate with respect to m), then let it equal to 0 and solve for m, make sure that the solution is positive.

    2.i 180 is correct.

    2ii) you have to solve the equation,



    The answer has to be greater than 6 since it occurs after reaching the maximum height.
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    Re: maxima minima help

    Quote Originally Posted by integral95 View Post
    1. you find dR/dm (differentiate with respect to m), then let it equal to 0 and solve for m, make sure that the solution is positive.

    2.i 180 is correct.

    2ii) you have to solve the equation,



    The answer has to be greater than 6 since it occurs after reaching the maximum height.
    thank you!!

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    Re: maxima minima help

    Quote Originally Posted by integral95 View Post
    1. you find dR/dm (differentiate with respect to m), then let it equal to 0 and solve for m, make sure that the solution is positive.

    2.i 180 is correct.

    2ii) you have to solve the equation,



    The answer has to be greater than 6 since it occurs after reaching the maximum height.
    can you please help with one last one
    A piece of wire 20cm in length is bent to form a rectangle. Find the dimensions of the rectangle so as to enclose maximum area

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    Re: maxima minima help

    Quote Originally Posted by sssona09 View Post
    can you please help with one last one
    A piece of wire 20cm in length is bent to form a rectangle. Find the dimensions of the rectangle so as to enclose maximum area
    The perimeter of the rectangle is obviously 20cm. Let the sides be and , and then find in terms of . Once both sides are expressed in terms of , you can obtain a formula for area which you can then differentiate.

    For reference, your area formula should be (oops!).
    Last edited by fan96; 9 Dec 2017 at 11:50 AM.
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    Re: maxima minima help






    Im learning too so i just planned to give it a try and post the working out for people who might need help

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