Question

Find the value of x3 + y3 if x + y = 3 and xy = 2.

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Answer 1

EXPLAINATION:

x3 + y3 = ?

x3 + y3 =(x + y) (x2 - xy + y2) ------ eqn 1

Now we don't no the value of x2 + y2

now We have the formula for finding x2 + y2

(x + y)2 =x2 + y2 +2xy

substitute in the following formula

you guys will get :

(3)2 = x2 + y2 + 2(2)

9 = x2 + y2 +4

x2 + y2 = 5

so let's substitute in the formula in eqn 1

we get : x3 + y3 = (3)(5-2)

=3*3

=9

therefore x3 + y3 = 9

I hope this answer will definitely help you guys thanq