length times width and getting a new equation for area?

cherryperry · February 13th, 2016, 10:48 AM

So here's my problem.

l = 52 - 2w

I need to write an equation for area based on width using the above equation. What am I missing here? Whatever the equation is, I have to enter it into my calculator to see the parabola, get the vertex, etc. I just can't figure out what the equation is I'm supposed to enter.

Any info would be appreciated. Thanks!

v8archie · February 13th, 2016, 10:50 AM

$A=lw$, and $l=52-2w$, so substitute.

cherryperry · February 13th, 2016, 11:01 AM

Thanks. Still confused though!

We're using a word problem asking about 52 panels, each 1ft long. The back of a house will close in one side of the patio. The question is:

Generalize a model (equation) for calculating the length (l) in terms of the width (w).
Hint: work from perimeter: P=2l +2w

I'm assuming I'm right with the first part (l = 52 - 2w). But nothing I graph shows a parabola.

greg1313 · February 13th, 2016, 12:16 PM

What is the exact problem statement (as worded by your instructor)? Include all given information.

February 13th, 2016, 10:48 AM	#1
cherryperry Newbie Joined: May 2010 Posts: 6 Thanks: 0	length times width and getting a new equation for area? So here's my problem. l = 52 - 2w I need to write an equation for area based on width using the above equation. What am I missing here? Whatever the equation is, I have to enter it into my calculator to see the parabola, get the vertex, etc. I just can't figure out what the equation is I'm supposed to enter. Any info would be appreciated. Thanks!
$cherryperry is offline$

February 13th, 2016, 10:50 AM	#2
v8archie Math Team Joined: Dec 2013 From: Colombia Posts: 7,599 Thanks: 2586 Math Focus: Mainly analysis and algebra	$A=lw$, and $l=52-2w$, so substitute.
$v8archie is offline$

February 13th, 2016, 11:01 AM	#3
cherryperry Newbie Joined: May 2010 Posts: 6 Thanks: 0	Thanks. Still confused though! We're using a word problem asking about 52 panels, each 1ft long. The back of a house will close in one side of the patio. The question is: Generalize a model (equation) for calculating the length (l) in terms of the width (w). Hint: work from perimeter: P=2l +2w I'm assuming I'm right with the first part (l = 52 - 2w). But nothing I graph shows a parabola.
$cherryperry is offline$

February 13th, 2016, 12:16 PM	#4
greg1313 Global Moderator Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,912 Thanks: 1110 Math Focus: Elementary mathematics and beyond	What is the exact problem statement (as worded by your instructor)? Include all given information.
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