1. Linear dependence and indipendence

I have a question for the following example that i read from a book which is:-

Show that the functions $y_1=x^2, y_2=5x, y_3=2x$ are linearly dependent on any interval.

and the solution for the example from the book

Solution. $y_2=0y_1+2.5y_3$. (I didn't understand this??)
This prove linear dependence on any interval.

p/s: Can anybody help me with this. I know the Wronskian and the quotient thing but i didn't understand at all about this example. I get this example from ADVANCE ENGINEERING MATHEMATIC, Kreyzsig, 9th edition, chapter 3.1, example 1

2. yap.. it was very easy actually.. maybe i was thinking too hard that i cannot even understand the simplest example. thanx, you are very helpful.

3. You're welcome ^^