Understanding the Role of Matrix Multiplication in Solving Equations

[Martin V.]

Hello hope you can help me.

Can anybody tell me what goes on from equation 3 to 4. especially how

gets in?

 

[RUber]

Note that $\overline{Y}(n \overline{X}^2 ) = \overline{X}(n \overline{X}\overline{Y}).$ This means that from 3 to 4, there was an addition of zero...likely to make the step from 4 to 5 more clear.

 

[Martin V.]

That right - thank you!