@khanacademy I think this can be solved without Calculus...
Can you use calculus to find the maximum perimeter for this rectangle? http:/khan.co/1LSqoC6pic.twitter.com/W13QQtZkro
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@amichaelberman@khanacademy It can be done with completing the square, for example. - 1 more reply
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@khanacademy You have brought my grade down throughout the year so I could use these 10 ec point on my final pls rtpic.twitter.com/DhDSr1mODC
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@khanacademy p=4x + 2*f(x)=8+4x-2x^2. Find maximum by taking derivative of p and setting equal to zero and solving for x. x=1. p(1)=10. no?Thanks. Twitter will use this to make your timeline better. UndoUndo
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@khanacademy that's my kid showing off his skills!! @superjet77791Thanks. Twitter will use this to make your timeline better. UndoUndo
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@khanacademy P(x) = 4x + 2*(4 - x^2) P'(x) = 0 when x = 1 P(1) = 10. Therefore 10 is the maximum perimeter of the rectangle.Thanks. Twitter will use this to make your timeline better. UndoUndo
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@graspsql
@khanacademy The rectangle stretches from -x to x and from 0 to y. So perimeter is 4x +2y.Thanks. Twitter will use this to make your timeline better. UndoUndo
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@khanacademy 21.33.....whats the answerThanks. Twitter will use this to make your timeline better. UndoUndo
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@khanacademy Let P=perimeter of rectangle. P=4x+2[f(x)]=4x+8-2x^2; P'=4-4x; Solve x for P'(x)=0 (zero slope@max),x=1; P(1)=10=max perimeterThanks. Twitter will use this to make your timeline better. UndoUndo
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