Some confusion over some indices questions

I am currently doing some algebra practice for English pre A Level Maths. I am doing examples of a worksheet and I am finding a few problems that have cropped up so far that I would greatly appreciate if someone could explain how to get the right solution as my algebra is pretty patchy in places and needs to be mastered! (Happy)

Here are they are:

**Simplify the following expressions into their simplest form**

**1,**

I simplfied to:

The answer in the back of the book:

?

**2,**

I simplified to:

Answer in the back of the book:

?

**3,**

I simplified to:

The answer im the back of the book:

?

Thanks in advance.

David