Question

x^3-8y^3+27+18xy factorise​

Answer 1

The correct question is :

Factorise the following term : x^3-8y^3-27-18xy

Solution :

x^3  + (−2y)^3  + (−3)^3  − 3.x.(−2y).(−3)

It is in the form of :  a^3  + b^3  + c^3  − 3abc' where a = x, b = -2y and c = -3

As we know that : a3+b3+c3-3abc=(a+b+c)(a^2+b^2+c^2-ab-bc-ac)

Hence, x^3-8y^3-27-18xy = (x−2y−3)(x^2 +4y^2 +9+2xy−6y+3x)