SOLUTION: If the sides of a swuare ae lengthened by 7 cm, the area becomes 144 cm^2. Find the lenght of a side of the original square. I come up with 29 cm for the answer but not sure if thi

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Question 186002: If the sides of a swuare ae lengthened by 7 cm, the area becomes 144 cm^2. Find the lenght of a side of the original square. I come up with 29 cm for the answer but not sure if this is correct. Can you help me with this. I thank you in advance for all your help.
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
If the sides of a swuare ae lengthened by 7 cm, the area becomes 144 cm^2. Find the lenght of a side of the original square. I come up with 29 cm for the answer but not sure if this is correct. Can you help me with this. I thank you in advance for all your help.

No, the length of a side of the original square was only 5 cm. 

We start with this little square with 5 cm on a side:

drawing%28175%2C175%2C1%2C7%2C1%2C7%2Cgrid%281%29%29+ 

and then if we increase the sides by 7 cm each, we get 
this large square, which we can easily see has an area 
of 144 little square centimeters.

drawing%28375%2C375%2C1%2C14%2C1%2C14%2Cgrid%281%29%29+

Here is how to work it out:

Let x cm be the length of a side of the original square.
Then when we increase the length of a side by 7 cm, each
side will then be x+7 cm.  Then we use the formula for
the area of a square, 

Area+=+side%5E2
144+=+%28x%2B7%29%5E2
Take square roots of both sides:
sqrt%28144%29+=+sqrt%28%28x%2B7%29%5E2%29
12+=+x%2B7
Subtract 7 from both sides
5+=+x

So the original square was 5 cm om a side.

Edwin