Hey, was wondering if someone could help me get on the right track with this problem i have to solve for homework.
I have to prove that the Sum of Squares total corrected is Y'Y-nӯ² using (Y- Ӯ)'(Y-Ӯ)

So what i have done so far is bring the transpose inside the first bracket: (Y'-Ӯ')(Y-Ӯ)
and then expanded the brackets: Y'Y-Y'Ӯ-Ӯ'Y+Ӯ'Ӯ
I then looked at the last part Ӯ'Ӯ which i think equals nӯ² so i just need to prove that the middle part( -Y'Ӯ-Ӯ'Y) is equal to -2nӯ² and then i will have completed the proof, but im not sure how to do this last part.
Anyone able to help? Please and Thank you