Answer :
(a+b+c)^3=a^3+b^3+c^3+3(a+b)(b+c)(c+a)
(a+b+c)^3-a^3-b^3-c^3=a^3+b^3+c^3+3(a+b)(b+c)(c+a)-a^3-b^3-c^3
⇒3(a+b)(b+c)(c+a)
(a+b+c)^3-a^3-b^3-c^3=a^3+b^3+c^3+3(a+b)(b+c)(c+a)-a^3-b^3-c^3
⇒3(a+b)(b+c)(c+a)
(a+b+c)³ = a³ + b³ + c³ + 3(a+b)(b+c)(c+a)
LHS = (a+b+c)³ - a³ - b³ - c³
= [a³ + b³ + c³ + 3(a+b)(b+c)(c+a)] - a³ - b³ - c³
= 3(a+b)(b+c)(c+a)
= RHS
LHS = (a+b+c)³ - a³ - b³ - c³
= [a³ + b³ + c³ + 3(a+b)(b+c)(c+a)] - a³ - b³ - c³
= 3(a+b)(b+c)(c+a)
= RHS