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For what positive value of \(m\) will the following equation be true if \(n=5\)?\(  (m + n)^2 + (m - n)^2 + m^2 + n^2 = 318. \)

 Jun 18, 2019
 #1
avatar+101856 
+2

(m + 5)^2 + (m - 5)^2 + m^2 + 5^2 = 318       simplify

 

m^2 +10m + 25 + m^2 - 10m + 25 + m^2 + 25 = 318

 

3m^2 + 75   = 318     subtract 75 from both sides

 

3m^2 = 243        divide both  sides by 3

 

m^2 = 81         take the positive  square root

 

m = √81

 

m  =  9

 

cool cool cool

 Jun 18, 2019
 #2
avatar+208 
+1

Nice CPhill! 

NoobGuest  Jun 18, 2019

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