What is the value of (a + b + 2c) (a2 + b2 + 4c2 - ab - 2abc - 2ca)?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. a3 + b3 + 8c3 - 6abc.
(a + b + 2c)(a2 + b2 + 4c2 - ab - 2abc - 2ca)
= (a + b + 2c)[a2 + b2 + (2c)2 - ab - 2abc - 2ca)
= a3 + b3 + (2c)3 - 3 × a × b × 2c
= a3 + b3 + 8c3 - 6abc