# math

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faye has 20 feet of fencing to make a rectangular pen for her dog.What is the largest area she can fence in?

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20 feet

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is that right im just gessing

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Let's see --
it could be 5 + 5 + 5 + 5
or 4 + 4 + 6 + 6
or 3 + 3 + 7 + 7

Find the areas of these pens.

A = length times width

So -- a 3 foot by 7 foot pen would be 21 square feet.

Find the areas of the other two pens. Which gives you the most square feet?

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For a math question:
Make a table of width (W) and lengths (L) that add up to 20 for perimeter = 2(W+L).
Calculate the area for each line. Choose the biggest area.
Width Length Area
1 9 9
2 8 16
3 7 21
4 6 24
.....
8 2 16
9 1 9

For a calculus question:
Let W=width, then
(10-W)=length, and
Area=A(W)=W(10-W)=10W-W²
For maximum or minimum:
dA/dW=10-2W=0, or W=5
d²A/dW²=-2 <0 so maximum.
A(5)=5(10-5)=25 (maximum area)

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hi im only in 4th grade so i really kind of need simple answers

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thanks ms.sue u rock

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You're welcome, Alex. :-)

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