Raven W.

asked • 04/09/15

The area of a square table, is numerically equal to triple its perimeter find the length of a side of a square and then Find the area of the square

Using GCF

1 Expert Answer

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Sahil P. answered • 04/09/15

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Raven W.

So can I substitute any number for s since they didn't give me a number to start with? I'm still a little confused 
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04/09/15

Sahil P.

No, what I mean by substitute is that you can substitute the equations for Area and Perimeter of a square into the equation at the top.  You can then solve for s.  
 
Hope that helps!  If you're still having trouble, get as far as you can and then let me know what you have so far so I can explain it further if needed!  Good luck!
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04/09/15

Raven W.

A= 4*4=16
P=4*16=64
then 3*64=192 ?? Is this right 
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04/09/15

Sahil P.

No, but let me show you why that is incorrect first.  
 
If A = 4*4=16, then P cannot be 4*16 since you just used 4 as "s".  
 
What I am saying is, you don't have to guess any numbers for the length of a side of a square.  Use the equation A=s*s and the equation P=4*s in the first equation, A=3*P, which is from the wording of the question.  
 
So if you substitute these equations for area and perimeter into the first equation, you get s*s = 3*(4*s). 
 
You can take this equation and solve for s.  There will be 2 mathematical solutions like I said, but only one will make sense for the length.  
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04/09/15

Raven W.

Ohhh so you have 3*(4*s)  then it's going to be 12*3s than you divide by 3s on both sides and it's going to give you 4=s ?? I hope I'm getting closer..
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04/09/15

Sahil P.

Getting closer!  :)
 
3*(4*s) is not 12*3s.  Look at it as 3*(4s).  What is that going to be?  
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04/09/15

Raven W.

Would it be just 12s?
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04/09/15

Sahil P.

Yup. So what equation does that leave you with?
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04/09/15

Raven W.

I have no clue would it leave me with the area equation ?
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04/09/15

Sahil P.

So you are left with s*s = 12s.  You can now solve this equation by moving all variables to one side and factoring.  
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04/09/15

Raven W.

can you give me a hint on how to factor that... So now I have 12s*s*s
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04/09/15

Sahil P.

You can't just move the 12s to the other side with the s*s in that way.  You can subtract it to get: s*s - 12s = 0.
 
So factor out an "s" to get s(s-12) = 0.  Now solve and you have your answer!
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04/09/15

Raven W.

Is that s^2-12s=0.. If Im wrong I'm soo sorry i know we been on this problem for a while 
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04/09/15

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