Question

If x+y= 8 and xy =15 find x3 +y3

Answer 1

hey friend

given that .

=)x+y = 8 ----------------(1)

=) xy = 15 ----------------(2)

from equation (1)

=) x+y = 8

cubing both sides

=)( x+y)^3 = 8^3

=) x^3 + y^3 + 3xy(x+y) = 512

=) x^3 + y^3 +3×15×8 = 512

=) x^3 +y^3 +360 = 512

=) x^3 + y^3 = 512 - 360

=) x^3 + y^3 = 152 ans.

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hope it helps

Answer 2

We need 2 numbers whose sum is 8 and product is 15 so we have
3 and 5

So now (3*3)+(5*3)=24