x+y=xy=3
find x^3 + y^3
Anyone? Could really use some help on this the extra credit would be nice to have.
The work is more important than the answer, so any idea on how to get started so i could begin figuring it would be much appreciated.
x+y=xy=3
find x^3 + y^3
Anyone? Could really use some help on this the extra credit would be nice to have.
The work is more important than the answer, so any idea on how to get started so i could begin figuring it would be much appreciated.
ok i'm still stuck. it's Find x^3 + y^3 so am i trying to cube the original equation? a bit more of a boost maybe?
i've got to be taking it in the wrong direction
i cubed the original equation and moved everything so it was x^3 + y^3= -3x^2y-3xy^2-x^3y^3-27
You have $\displaystyle x + y = 3$
So $\displaystyle (x + y)^3 = 27$
$\displaystyle (x + y)^3 = x^3 + 3x^2y + 3xy^2 + y^3$
$\displaystyle 27 = x^3 + 3x^2y + 3xy^2 + y^3$
$\displaystyle x^3 + y^3 = 27 - 3x^2y - 3xy^2 $
$\displaystyle x^3 + y^3 = 27 - 3xy(x + y) $
$\displaystyle x^3 + y^3 = 27 - 3 \times 3 \times 3 \quad$ (since x+y = 3 and xy = 3