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Lisa solved  3x2 + 1 = 28  as shown:

3x2 + 1 = 28 

3x2  = 27

   x2  = 9

 

She concluded that the solutions are x = -9   or   x = 9. 

 

1.  Using complete sentences, explain what mistake she made.

 

2.  What are the correct solutions?  

 Sep 25, 2018
 #1
avatar+99351 
+1

The mistake is that she forgot to take both square roots  of   9   =   3  or  -3

 

 

 

cool cool cool

 Sep 25, 2018

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