The lenght of a rectangle is 3cm greater than its width.the perimeter of the rectangle is 34cm.find its lenght.

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- Apr 19th 2014, 02:11 AMcharliecg61algebra
The lenght of a rectangle is 3cm greater than its width.the perimeter of the rectangle is 34cm.find its lenght.

- Apr 19th 2014, 02:37 AMprasumRe: 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, 01:21 PMJeffMRe: 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.

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

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

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

Fourth, check your answer.

7 + 3 = 10. Correct.

2 * 7 + 2 * 10 = 14 + 20 = 34. Correct.

If you remember to do these four steps for every word problem, you will soon find doing them correctly to be much easier.