Question 25

If $$ x^3 + y^3 = 9 $$ and x + y = 3, then find the value of 'xy'.

Solution

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$$x^3+y^3$$=9

or, $$(x+y)^3-3xy(x+y)$$=9.

or, $$3^3-3xy×3$$=9.

or, 9xy=27-9=18.

or, xy=2.

C is correct choice.

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