Simplify `(a-b-c)(a^2+b^2+c^2-ab+bc-ca)`

Find the product of (a+b+2c)(a^2+b^2+4c^2 -ab-2bc-2ca) . (a+b+2c)(a^2+b^2+4c^2 -ab-2bc-2ca) का गुणनफल ज्ञात करें ।

If a^2 + b^2 + c^2 - ab - bc - ca = 0 , then prove that a=b=c.