Quadratic Equation Help

[sillygirl]

Please help on this question. I am completely lost on how to do it. Thank you!
**Please note I would like to have 800 square feet for my animal***

Congratulations, you have just purchased your first house. Unfortunately, the builder forgot to put a fence around the property and you must now put a fence up so that you can let your pet out in the backyard, without fear of it running away.

You want to fence in a rectangular area, but first you must determine the dimensions of the area.

Define the shape of the rectangular area by establishing a relationship between the length and width of the rectangle. For example, L = 2W + 5, or W = 3L – 4. Be sure to include the appropriate units (inches, feet, yards, miles, or meters).

Using the fact that A = LW, together with the relationship defined in step 2, eliminate one of the variables to set up a quadratic equation.

Now determine the perimeter so that you will know how much fencing to buy.

 

[tkhunny]

in the backyard, without fear of it running away.

First off, why would your back yard run away?

2nd, have you tried either of the suggestions?

3rd, you cannot be "completely lost", since the problem statement walks you through it.

 

[mmm4444bot]

I would like to have 800 square feet for my animal

This statement tells us what the units need to be on the length and width.



Define the shape of the rectangular area by establishing a relationship between the length and width of the rectangle.

For example, L = 2W + 5, or W = 3L – 4

The example relationship between L and W listed as L = 2W + 5 says that the length of the yard is five feet more than twice the width of the yard.

The example listed as W = 3L - 4 says that the width is four feet less than three times the length.

Those are examples. Unless they gave you additional information about how the length and width are related, I think that you are supposed to make up your own relationship between L and W. Can you do that?



Using the fact that A = LW, together with the relationship defined in step 2, eliminate one of the variables to set up a quadratic equation.

I'm not sure what step 1 is because only one step has been mentioned, up to this point.

And, the phrase "eliminate one of the variables" simply means to substitute into the equation A=L*W the expression for the length (or width) that you defined in step 2. This leads to an equation that contains only one variable.

I'll show you the substitution, using one of the given example relationships between length and width.

L = 2W + 5

This equation is a definition for symbol L. We now have two ways to express the length. We can use the expression L, or we can use the expression 2W+5.

Both expressions represent the same number; so, we can substitute the expression 2W + 5 for the symbol L in the area equation.

800 = L*W

800 = (2W + 5)*W

This is a quadratic equation. We solve it for W.

After we determine the width of the yard, we substitute it into the definition L = 2W + 5, to find the length.


If you need more help, please ask specific questions. Also, check out the post titled "Read Before Posting" for guidelines on how to ask for help on these boards.

Cheers ~ Mark :cool: