a2 + b2 + c2 + 2ab + 2bc + 2ca = ………………. A) (a + b + c)2�

1.	a2 + b2 + c2 + 2ab + 2bc + 2ca = ………………. A) (a + b + c)2 B) (a – b – c)2 C) (2a – b – c)2 D) (a – b)2
Answer» A) (a + b + c)² Correct option is (A) \((a+b+c)^2\) \(a^2+b^2+c^2+2ab+2bc+2ca\) \(=a^2+b^2+2ab+2bc+2ca+c^2\) \(=(a+b)^2+2(a+b)c+c^2\) = \((a+b+c)^2\)

a2 + b2 + c2 + 2ab + 2bc + 2ca = ………………. A) (a + b + c)2 B) (a – b – c)2 C) (2a – b – c)2 D) (a – b)2

Answer»

A) (a + b + c)²

Correct option is (A) \((a+b+c)^2\)

\(a^2+b^2+c^2+2ab+2bc+2ca\) \(=a^2+b^2+2ab+2bc+2ca+c^2\)

\(=(a+b)^2+2(a+b)c+c^2\)

= \((a+b+c)^2\)