I have this problem to solve. It's been a while since I tried to figured out how to do, but I am totally lost.

Here it is.

Prove SST= SSW+SST in one-way Anova (one factor).

Σ ( xi - x̄ )² = Σ (xi - x̄ + x̄ k - x̄ k ) ²

Hint: Σ [ ( xi - x̄ k ) + ( x̄ k - x̄ )]²

Where should I start? Should I try to compute Σ [ ( xi - x̄ k ) + ( x̄ k - x̄ )]² in order to come up with SST= Σ ( xi - x̄ )²

Seriously, I have no idea ...

Any help ? :shakehead