Why can 2x−3 be rewritten as 2x in a Wronskian?

[Calpalned]

Homework Statement

Page 133

Homework Equations

n/a

The Attempt at a Solution

What is the process for rewriting the third column? 2x-3 and be rewritten as 2x, and 2-3cosx can be rewritten as 2.
I don't get this.

 

[Dick]

Homework Statement

View attachment 90476
Page 133

Homework Equations

n/a

The Attempt at a Solution

What is the process for rewriting the third column? 2x-3 and be rewritten as 2x, and 2-3cosx can be rewritten as 2.
I don't get this.

They are adding 3 times the second column to the third.