If:

X+1/X=4

then what is the value of

X^3+1/x^3

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- Nov 7th 2006, 03:38 PMRimasAlgebra
If:

X+1/X=4

then what is the value of

X^3+1/x^3 - Nov 7th 2006, 03:44 PMDergyll
Hi

Im just going to do this the classic/stupid way.

Solve for x in x+1/x=4 and you get x=1/3, then substitude it into the other equation and bam you got the answer.

THere's probably a better, more efficient way though...

Derg - Nov 7th 2006, 04:23 PMSoroban
Hello, Rimas!

This problem has a spectacular solution . . .

Quote:

If

then what is the value of

Cube the equation: .

We have: .

Then: .

. . . . . . .

. . . . . . . . .