Urgent: Surd help :)

[Lemon]

Hey guys, i am doing some revision because throughout year 11 i can see i've had problems with the easy stuff instead of the hard. I couldn't factorise to the potential you had to have and stuff like that. Now i'm doing my revision so i'm sharp so when year 12 starts i don't have to worry about simple things like that.

Anyways, my problem is surds

Question: 1

at the end of this problem, i get

meaning i rationalized it and everything, but see, the answer is

(that minus changed and moved in-front of the 6, i get it a little but i need to understand why that happens. Please explain

Question: 2

in the end of this problem, i get

but from the previous problem, i see we need to move the negative outside the fraction (if that's what it means), so i get

, now i see you can simplify the 4√(18) further, which means the answer turns to

. Now in the book. it says the answer is

(the minus is in-front of the two), my question is why was the 2 taken out when the 4√(18) was simiplified further.. :S



Please help me understand this and thanks