[SPLIT] length of a rectangle is 3 more than twice its width

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
User avatar
Xo Exia oX
Posts: 18
Joined: Wed Jul 08, 2009 12:59 am
Contact:

[SPLIT] length of a rectangle is 3 more than twice its width

Postby Xo Exia oX » Thu Jul 30, 2009 11:25 pm

I have another problem I can't solve.
The length of a rectangle is 3 more than twice its width. The perimeter is 48 feet. Find the width.


I came up with an equation 2w + 3 + w = 48.

When I solved, W = 15. There is no choice for 15.

User avatar
stapel_eliz
Posts: 1733
Joined: Mon Dec 08, 2008 4:22 pm
Contact:

Postby stapel_eliz » Fri Jul 31, 2009 12:15 am

Check the formula for "perimeter". I'm fairly certain it's P = 2L + 2w, not P = L + w. :wink:

User avatar
Xo Exia oX
Posts: 18
Joined: Wed Jul 08, 2009 12:59 am
Contact:

Re: [SPLIT] length of a rectangle is 3 more than twice its width

Postby Xo Exia oX » Sat Aug 01, 2009 6:52 pm

I tried again, and came up with 2w + 3 + 2w = 48

Solve for W = 11.25

User avatar
stapel_eliz
Posts: 1733
Joined: Mon Dec 08, 2008 4:22 pm
Contact:

Postby stapel_eliz » Sat Aug 01, 2009 7:05 pm

You don't show much work, so I can only guess that you're trying to do too much at once. Instead, trying working step-by-step and clearly.

Write down your explicit variable for the width.

Write down your explicit expression for the length, in terms of the variable for the width.

Plug the variable in for "w" in the "perimeter" formula.

Plug the expression in for "L" in the "perimeter" formula.

Plug the given value in for "P" in the "perimeter" formula.

Solve this equation for the variable.

User avatar
Xo Exia oX
Posts: 18
Joined: Wed Jul 08, 2009 12:59 am
Contact:

Re: [SPLIT] length of a rectangle is 3 more than twice its width

Postby Xo Exia oX » Sun Aug 02, 2009 7:27 pm

1. W

2. 2w + 3

3. P = 2(w) + 2L

4. P = 2(w) + 2(2w + 3)

5. 2W + 4W + 3 = 48

6W + 3 = 48

48 - 3 = 45

6w = 45
/6 /6

w = 7.5

User avatar
stapel_eliz
Posts: 1733
Joined: Mon Dec 08, 2008 4:22 pm
Contact:

Postby stapel_eliz » Sun Aug 02, 2009 8:44 pm

Xo Exia oX wrote:4. P = 2(w) + 2(2w + 3)

5. 2W + 4W + 3 = 48

2(2w + 3) = 2(2w) + 2(3) = ...?

:wink:

User avatar
Xo Exia oX
Posts: 18
Joined: Wed Jul 08, 2009 12:59 am
Contact:

Re: [SPLIT] length of a rectangle is 3 more than twice its width

Postby Xo Exia oX » Mon Aug 03, 2009 3:38 am

W = 7

Thanks!! :D


Return to “Intermediate Algebra”