SOLUTION: if x+y=3 and x^2+y^2=6, find the numerical value of x^3+y^3

Question 1091393: if x+y=3 and x^2+y^2=6, find the numerical value of x^3+y^3
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

This is a type of algebra problem commonly encountered on high school math contests.

You need to use the given equations somehow to get an expression containing x^3 and y^3. One way to do this is to cube the first equation:

You know the value of (x+y); to get a numerical value for this expression, you need to find the value of xy. To do that, you can square the first equation:

And finally

Another way to get an expression that includes x^3 and y^3 is to multiply the two given equations together.

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