SOLUTION: IF x=1+3+3^2+3^3+3^4+3^5+3^6+3^7+3^8+3^9+3^10 then y=3x+1 What is the value of x-y?

Algebra ->  Expressions-with-variables -> SOLUTION: IF x=1+3+3^2+3^3+3^4+3^5+3^6+3^7+3^8+3^9+3^10 then y=3x+1 What is the value of x-y?      Log On


   

Question 504502: IF x=1+3+3^2+3^3+3^4+3^5+3^6+3^7+3^8+3^9+3^10
then y=3x+1
What is the value of x-y?
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
(I'll use sigma notation to make it more compact)

If

, then

, and



Therefore,



The 3^1, 3^2, ..., 3^10 will cancel, leaving

as our answer.