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Hello,

X + 1/X = 3 , then X^2 + 1/X^2 =.........

I tried solving it million times but yet i didn't find the correct answer..

It is 7 but i don't know the proof or how the model answer got it.

I got 9 by:

Square both sides

X^2 + 1/X^2=9 = X^2 + 1/X^2 = 9 as well?

 May 2, 2019
 #1
avatar+106539 
+2

x + 1/x  = 3         square both sdes

 

(x + 1/x)^2  = 3^2         simplify

 

x^2  + (x)(1/x) + (x)(1/x) + (1/x)^2  = 9

 

x^2  +  1  + 1   + (1/x^2)  = 9

 

x^2 + 2 + (1/x)^2  = 9      subtract 2 from both sides

 

x^2 + (1/x)^2  = 7           ....and there you go   !!!

 

 

cool cool cool

 May 2, 2019
edited by CPhill  May 3, 2019
 #2
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+1

Man can't thank you enough :) 

Guest May 2, 2019
 #3
avatar+106539 
+1

OK....glad to help  !!!!!

 

 

 

cool cool cool

CPhill  May 2, 2019
 #4
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At (1/x62) ... Shoulda held down the shift key to type a ^ instead of a 6. 

1/x^2

Guest May 3, 2019

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