Sunday

April 20, 2014

April 20, 2014

Posted by **alex** on Monday, October 5, 2009 at 4:33pm.

- math -
**alex**, Monday, October 5, 2009 at 4:34pm20 feet

- math -
**alex**, Monday, October 5, 2009 at 4:38pmis that right im just gessing

- math -
**Ms. Sue**, Monday, October 5, 2009 at 4:39pmLet'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?

- math -
**MathMate**, Monday, October 5, 2009 at 4:39pmFor 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)

- math -
**alex**, Monday, October 5, 2009 at 5:15pmhi im only in 4th grade so i really kind of need simple answers

- math -
**Ms. Sue**, Monday, October 5, 2009 at 5:27pmPlease see my answer. I'm sure you can figure out your answer using that information.

- math -
**alex**, Monday, October 5, 2009 at 5:28pmthanks ms.sue u rock

- math -
**Ms. Sue**, Monday, October 5, 2009 at 5:30pmYou're welcome, Alex. :-)

**Related Questions**

Math - Laura has 20 feet of fencing to make a rectangular pen for her dog. What ...

Math - Can you please help me figure out what to do? ... here is the question...

math - A farmer will make a rectangular pen with 100 feet of fence using pasrt ...

Pre-Calc - A farmer is making a pig pen next to the barn. He has enough ...

math - a farmer has enough fencing to build 40 feet of fence. He wishes to build...

algebra - Marcus has 72 feet of fencing. He wants to build a rectangular pen ...

Math - Jennifer plans to fence a rectangular area around her rectangular ...

math - Howard has 102 feet of fencing. What is the area of the largest square ...

calculus - a farmer wants to make a rectangular pen from 200 feet of fencing. he...

Math please help - A farmer has 120 feet of fencing available to build a ...