+0  
 
0
768
2
avatar

the perimeter of a rectangle is 44cm. the length is 7 more then twice the width. what is the length/width?

 Sep 3, 2014

Best Answer 

 #2
avatar+26367 
+5

the perimeter of a rectangle is 44cm. the length is 7 more then twice the width. what is the length/width?

width of the rectangle: W

length of the rectangle: L

the perimeter: $$p = 2 * ( L+W ) = 44\;cm \quad \mbox{or} \quad \boxed{L + W = 22 \;cm \qquad (1)}$$

the length is 7 more then twice the width: $$L = 7\;cm + 2W \quad \mbox{or} \quad \boxed{L - 2W = 7\;cm \qquad (2)}$$ 

 

 $$\begin{array}{lrcl}
(1) - (2):&\\
&\underbrace{L-L}_{=0}+\underbrace{W-(-2W)}_{=3W}&=&\underbrace{22 cm - 7cm}_{=15\;cm}\\
&3W&=&15\;cm \quad | \quad : 3\\
&W&=&5\;cm
\end{array}$$

 

$$\begin{array}{rcl}
L + W &=& 22\;cm\\
L &=& 22 \;cm- W \\
L&=& 22\;cm- 5 \;cm\\
L &=& 17 \;cm
\end{array}$$

 Sep 3, 2014
 #1
avatar+4473 
0

Let's set up an equation after defining some variables:

 

L = length & W = width

 

L = 2W + 7 (length is 7 more than twice the width)

 

Perimeter of a rectangle is 2L + 2W...

 

2(2W + 7) + 2W = 44.

 

Distribute the 2.

4W + 14 + 2W = 44.

 

Combine like terms and subtract 14 from both sides.

6W = 30.

 

Solve for W.

W = 30/6 = 5.

 

So, L = 2W + 7 = 2(5) + 7 = 10 + 7 = 17.

 

L = 17 cm.

W = 5 cm.

 

Check: 2L + 2W = 44. 

2(5) + 2(17) = 44.

 

10 + 34 = 44. Yes.

 Sep 3, 2014
 #2
avatar+26367 
+5
Best Answer

the perimeter of a rectangle is 44cm. the length is 7 more then twice the width. what is the length/width?

width of the rectangle: W

length of the rectangle: L

the perimeter: $$p = 2 * ( L+W ) = 44\;cm \quad \mbox{or} \quad \boxed{L + W = 22 \;cm \qquad (1)}$$

the length is 7 more then twice the width: $$L = 7\;cm + 2W \quad \mbox{or} \quad \boxed{L - 2W = 7\;cm \qquad (2)}$$ 

 

 $$\begin{array}{lrcl}
(1) - (2):&\\
&\underbrace{L-L}_{=0}+\underbrace{W-(-2W)}_{=3W}&=&\underbrace{22 cm - 7cm}_{=15\;cm}\\
&3W&=&15\;cm \quad | \quad : 3\\
&W&=&5\;cm
\end{array}$$

 

$$\begin{array}{rcl}
L + W &=& 22\;cm\\
L &=& 22 \;cm- W \\
L&=& 22\;cm- 5 \;cm\\
L &=& 17 \;cm
\end{array}$$

heureka Sep 3, 2014

2 Online Users