SOLUTION: I just finished a math exam and theres one question that I just couldn't figure out. It went like this: "A rectangular field has an 800m long fence around the perimeter. The area o

Question 463891: I just finished a math exam and theres one question that I just couldn't figure out. It went like this: "A rectangular field has an 800m long fence around the perimeter. The area of the field is 37500m^2. What are the diemensions of the field." I think im supposed to use Substitution so I wrote the formulas I know that relate to the question and I plugged in the information from the question into the equation so it was like this: "P(perimeter)=2*L(length)+2*width & A(area)=L*W. After this I dont know what to do. I can eliminate be the operations are different so the only option is to change an equation to isolate a variable to substitute it into the next equation but I don't know. No hurry gettin back to me the exams already done im just asking to ease my mind
Answer by richard1234(7193) (Show Source): You can put this solution on YOUR website!
We know the perimeter is 800 m and the area is 37500m^2, so

800 = 2L + 2W --> L + W = 400

LW = 37500

From the equation L + W = 400 we can isolate L and say L = 400 - W. Plug this into the expression for area:

(400-W)W = 37500

-W^2 + 400W - 37500 = 0

W^2 - 400W + 37500 = 0

By factoring or by the quadratic formula, we get W = 150 or W = 250. This implies the other dimension is 250 or 150 (order doesn't matter since we can choose a different L. The dimensions are basically 150x250).
RELATED QUESTIONS
This is driving me crazy. I finally solved my problem, but I can�t figure out why my... (answered by kensson,MathTherapy)

Hello theres one question on my alegebra that i just cannot figure it's: How many liters... (answered by nerdybill,ewatrrr)

I might not have the topic exactly right, but I have an issue. This assignment was due... (answered by josgarithmetic,Edwin McCravy,MathLover1,ikleyn)

i'm not quite sure if this is evaluation of expressions, parentheses, i'm just confused!... (answered by Fombitz)

PLEASE help me with this.... one side of a triangle has a length of 5x-2. a longer side... (answered by bucky)

for this aint a math question but want to know. for I am a tutor just like you started... (answered by longjonsilver)

I need help I am adding and subtracting polynomials and I get it and I understand the... (answered by stanbon)

Okay, so I'm really struggling on this question, and I was wondering if someone could... (answered by MathLover1,ikleyn)

Hi, earlier I posted my math problem but I couldn�t figure out how to upload the image so (answered by greenestamps)