Matrix transformations

[SamuelGHOSTY]

I found a book (http://hades.mech.northwestern.edu/images/7/7f/MR.pdf#page=531&zoom=100,0,222 (page 517)) and there are some equations that bugs me. On pictures you can see that with equations from pictures 1 and 2 we can get equation on picture 4. How does that happen? I tried to solve it by myself but I got different first row in equation on picture 4. It will be much better if you show me how to get the last equation step by step. All Beta i equal to 0. l and w are shown in the picture 3 (those are lengths). wbz is an input variable, we doesnt need to know what it equals to for now.

Edited January 8, 2019 by SamuelGHOSTY

[studiot]

And what would the Beta i be?,

Edit and the w?

Edited January 8, 2019 by studiot