# algebra

• Apr 19th 2014, 03:11 AM
charliecg61
algebra
The lenght of a rectangle is 3cm greater than its width.the perimeter of the rectangle is 34cm.find its lenght.
• Apr 19th 2014, 03:37 AM
prasum
Re: algebra
width=x
length=x+3
perimeter=2*(l+b)=34cm(given)
2(x+x+3)=34
2x+3=17
x=7
length=x+3=7+3=10cm
• Apr 19th 2014, 02:21 PM
JeffM
Re: algebra
Notice what prasum did. It is a procedure that works for every word problem.

First, name your variables in writing.

\$width = W.\$

\$length = L.\$

\$perimeter = P.\$

Second, take all the information that you are given explicitly in the problem or that you are implicitly expected to know and translate it into math speak in writing.

\$P = W + L + W + L = 2W +2L.\$

\$P = 34.\$

\$L = W + 3.\$

\$Find\ value\ of\ L.\$

Third, you now have a pure math problem; all the words are gone. Solve that problem.

\$34 = P\ and\ P = 2W + 2L \implies 2W + 2L = 34.\$

\$L = W + 3 \implies 2L = 2(W + 3) = 2W + 6.\$

\$So\ 2W + (2W + 6) = 34 \implies 2W + 2W + 6 = 34 \implies 4W = 28 \implies W = 7 \implies L = 10.\$