Question 1126980
Note that (a^3+b^3) = (a+b)(a^2−ab+b^2)
:
(x^3+y^3)+10xy = (x+y)(x^2-xy+y^2) +10xy =
:
3(x^2-xy+y^2) +10xy =
:
3x^2 -3xy +3y^2 +10xy =
:
3x^2 +7xy +3y^2
: