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Two sides of a square are represented by xsquared + 8x and 5x + 28. What is the perimeter of the square? 

Guest May 3, 2017
 #1
avatar+7023 
+1

Perimeter

= 2((x^2 + 8x) + (5x + 28))

= 2(x^2 + 13x + 28)

= 2x^2 + 26x + 56

MaxWong  May 3, 2017
 #2
avatar+7266 
+4

The sides of a square are the same length...so

x2 + 8x = 5x + 28      Subtract 5x from both sides.

x2 + 3x = 28              Subtract 28 from both sides.

x2 + 3x - 28 = 0         Factor.

(x + 7)(x - 4) = 0        Set each factor =0

x = -7    or     x = 4

 

If x = -7, the side length = (-7)2 + 8(-7) = -7

But since this is the length of a side, we want a positive number, so x must = 4

 

If x = 4, the side length = 42 + 8(4) = 48

 

perimeter = 4 * side length

perimeter = 4 * 48 = 192 units

hectictar  May 3, 2017
 #3
avatar+7023 
0

Wow.

I didn't even think of solving for x and I just thought it was a question to tell you express the perimeter in terms of x.....

I feel so embarrassed now blush

MaxWong  May 3, 2017
 #4
avatar+7266 
+1

Hey your answer isn't even technically wrong smiley

hectictar  May 3, 2017
 #5
avatar+7023 
0

But I did the wrong stuff I hate myself so much :(

MaxWong  May 3, 2017
 #6
avatar+7266 
+2

I do feel bad after I answer stuff wrong too..but there's really no need to!

It's really easy to miss a detail like that smiley

hectictar  May 3, 2017

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