Any math people? Help!

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monaxlisa

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Hey guys, I've got about 25 word problems that I'm trying to trudge through, I'm down to two that I cant figure out, and I know they're really simple!!!

A rectangular lot is surrounded on all sides by a driveway 3 yards wide. The lot is twice as long as it is wide. If the area of the lot and driveway together is 216 sq. yards, find the dimensions of the lot.

I've got it set up as an area problem (A=L*W) but it seems to be asking for the perimiter (P=2L+2W) and I'm just stuck! I cant get it set up right (2x-3 or 2x+3 or just 2x for L?) I would appreciate any help, once I get this one done I'll have the assignment finished!

(Thanks!)
 
tigerontheprowl

tigerontheprowl

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Originally Posted by MonaxLisa

Hey guys, I've got about 25 word problems that I'm trying to trudge through, I'm down to two that I cant figure out, and I know they're really simple!!!

A rectangular lot is surrounded on all sides by a driveway 3 yards wide. The lot is twice as long as it is wide. If the area of the lot and driveway together is 216 sq. yards, find the dimensions of the lot.

I've got it set up as an area problem (A=L*W) but it seems to be asking for the perimiter (P=2L+2W) and I'm just stuck! I cant get it set up right (2x-3 or 2x+3 or just 2x for L?) I would appreciate any help, once I get this one done I'll have the assignment finished!

(Thanks!)
Click to expand...
The equation I'd use for that is A=L*W. A=216 W=x+6 L=2x+6. So it becomes (2x+6)(x+6)=216 sq. yards where x refers to the width of the lot, 2x is the length and the +6 is for the driveways on each side. That gives you 2x^2+18x+36=216. 2x^2+18x=180. When you do the math after that you find that x=6. So the lot is 6 yards wide by 12 yards long.
 
ut0pia

ut0pia

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Originally Posted by kluchetta

So the area, 216 is (x+6) x (2x + 6)


I tried to draw it but failed.
Click to expand...
I think it's 216=(x+3)(2x+3) the lot is 3 ft wide not 6?????
I could be wrong...I wasn't great at math but I didn't fail either.
 
ut0pia

ut0pia

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Oh duhhh it would be 6 because it makes it longer by 3 on both sides...sorry lol
 
kluchetta

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Originally Posted by ut0pia

Oh duhhh it would be 6 because it makes it longer by 3 on both sides...sorry lol
Click to expand...
It's ok. I get stuck at

2x^2 + 18x = 180

I can't remember how to solve with that stupid x squared...
 
ut0pia

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Originally Posted by kluchetta

It's ok. I get stuck at

2x^2 + 18x = 180

I can't remember how to solve with that stupid x squared...
Click to expand...
a graphing calculator knows best

I remember factoring but I don't remember how to actually do it, so that doesn't help much.
 
kluchetta

kluchetta

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Originally Posted by ut0pia

a graphing calculator knows best

I remember factoring but I don't remember how to actually do it, so that doesn't help much.
Click to expand...
Maybe you use the quadratic formula?
 
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