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avatar+781 

If x+x+x+x+=9, find x.

 

 

 

I know that if this equation were switched around, where the x is 9 and 9 is x instead, we'd solve it like this:

 

9+9+9+9+=xx2=9+9+9+9+x2=9+xx2x9=0x=1+372

 

I think I should be applying the same logic, but it's kind of difficult because of the x and it's making me confused. Could anyone help?

 Jul 2, 2020
 #1
avatar+23254 
+1

Your instinct is correct!

 

Call that whose expression on the left side of the equal sign "expression" so you have

   [expression]  =  9

 

Square both sides  --  you'll get:

  x + [expression]  =  81

 

Since  [expression]  =  9  --  by substituting  '9'  for  [expression]  --  you'll now have:

  x + 9  =  81

 

Therefore,  x  =  72

 Jul 2, 2020
 #2
avatar+781 
+1

ah ok, I get it now. Thanks.

 Jul 2, 2020

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