how do you do this? i wanna learn how..
the length of a rectangle is twice the width find the length of the rectangle if the perimeter is 42 cm..
pleaaase explain

Question

mathteacher1729 · Answer

Length = L 
Width = W 

"the length of a rectangle is twice the width" as an equation is "L = 2W" 

The perimeter of a rectangle is 2L + 2W. 

So we sub L = 2W into (2L + 2W) and obtain 

(2(2W) + 2W) = 4W + 2W 
                     = 6W

But the perimeter is given as 42 cm so that means

6W = 42

now solve for W. :)

anonymous · Answer

Write equations for each aspect of the question.

L=Length
W=Perimeter

L=2W

And you know that the perimeter is the sum of the sides of the rectangle, so there are 2 lengths and 2 widths, which gives:

2L+2W=42

Now substitute L=2W into the above equation. 

6W=42
W=7

THis means that the length is 14 (L=2W)

anonymous · Answer

perimeter is 
$$P=2l+2w$$ and you know 
$$l=2w, P = 42$$ so set 
$$42=2\times 2w+2w$$
$$42=6w$$
$$\frac{42}{6}=w$$
$$7=w$$

anonymous · Answer

Use the verbal expressions; L=2W
Perimeter =2L +2W.  Substitute L for 2W and solve!

anonymous · Answer

would you do 42 divided by 6 t the end??
(thank ya'll!!!!!:Dl)

anonymous · Answer

at the end*

mathteacher1729 · Answer

Hi Blah blah, yes, you'd divide 42 by 6 at the end.  That would give you W. You still have to find L, though.  But that is easy, since L is 2W. :)

anonymous · Answer

tha answer iss...14?:O
sweeeeeeeeett.