SOLUTION: if x+1/x=3 then find the value of x^3+1/x^3

Question 1049594: if x+1/x=3 then find the value of x^3+1/x^3
Answer by ikleyn(52748) (Show Source): You can put this solution on YOUR website!
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if x+1/x=3 then find the value of x^3+1/x^3
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If  +  = 3 then 

27 =  =  +  +  +  =  +  +  +  =  +  +  + .


Now replace the term    before the last "1" by 3*3 = 9 (due to the condition !), and you will get

27 =  +  + 9 + 1.

And you need to make only one last step to get

 +   = 27 - 9 - 1 = 17.


Answer.  If  +  = 3 then   +  = 17.

For other similar problems see the lesson
- HOW TO evaluate expressions involving , and
in this site.

Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lesson is the part of this textbook under the topic "Evaluation, substitution" of the section "Word problems".

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