Question

If x+y=3 and xy=2, find x cube +y cube

Answer 1

Step-by-step explanation:

it is given that, x + y = 3 and xy = 2

firstly, (x+y) ^2 = x^2 + y^2 + 2xy

put the above values in it,

(3)^2 = x^2 + y^2 + 2(2)

x^2 + y^2 = 9-4

x^2 + y^2 = 3

now

x^3 + y^3 = (x + y)(x^2 - xy + y^2)

= (3)(3-2)

x^3 + y^3 = 3