Maxima and Minima Problem (1 Viewer)

[chloandrews]

Hey guys - could you please help me out with this problem:

The area of a rectangular sheet of paper is 600cm. A margin of 1.5cm is allowed at the top and bottom and 2.5cm on each edge. Find the exact dimensions of the printed area if it is to be maximised.

I'm usually okay with these not 100% sure why i'm not getting one this simple :/ .. thank you xx

 

[VBN2470]

I am getting dimensions of by .

Method: Let x and y be the sides of the rectangle so that xy=600. Then, since you only want to maximise an area where each side is shrunken by a margin, you would have (x-5) and (y-3) as your required dimensions for the area of the rectangle you wish to maximise. If we denote A(x)=(x-5)(y-3), then we can differentiate with respect to x, noting that and by algebraic substitution, we should get the required dimensions such that A is maximised.

Hope that helps