Cho a + b + c = 0. CMR: a^4 + b^4 + c4 = 1/2(a^2 + b^2 + c^2). Cho a + b + c = 0. CMR: 2(a^5 + b^5 + c^5) = 5abc(a^2 + b^2 + c^2)

1. Cho a + b + c = 0. CMR: a^4 + b^4 + c4 = 1/2(a^2 + b^2 + c^2)
2. Cho a + b + c = 0. CMR: 2(a^5 + b^5 + c^5) = 5abc(a^2 + b^2 + c^2)