Angry 9 yr old daughter

[marsmom2000]

I'm a single mother of a 9 year old girl.  She has always acted way more grown up than she is; however, lately she's been throwing major tantrums when she's told to do something she doesn't want to do or doesn't get her way.  She rolls her eyes, sticks out her tongue, and talks back - sometimes just when she's told to brush her teeth or take a shower.  From there it turns into a huge ordeal and she ends up screaming and crying.  She gets to the point where she tells me she hates me or wishes she was dead.  At one point she got so angry she told another family member she wanted to kill them.  She's not a trouble maker, she's very respectful of others and has no behavior problems at school.  It seems to only be her close family that she has no problem disrespecting.  Her father is basically not in her life.
Should I be concerned about the things she says, or just assume that it's something said in anger?  She's usually a cheerful, happy little girl who loves to joke around.  I can't understand where all this anger is coming from.  Also, any suggestions on how to handle all this anger?  It's hard to be sympathetic when it's usually brought on because she's not doing what she's supposed to do.

[mammo]

It's always imperative to teach children at a very young age that you are the parent, and you make the rules.  If she doesn't do as you say, there has to be reprocussions for her actions, and talking and threatening is just that.  She has to learn that you mean what you say and stick to it.  Don't argue with her, it's not up for debate.

[Sandman2]

   In a nutshell, she is using the anger (in my opinion) because she has found it gets results.  If it was also happening at school - where they are very demanding and rigid - it would be a different story.
   Also it may not be so much anger as a way she has found that works for her.  Either way - what do you do?  You ignore it.  You play the "broken record", by repeating what you want her to do.  You don't lower yourself to her level.  You stay calm.  Its ok to do a timeout till she calms down (she will go nuts when you say that, but thats ok and expected).  Always end the timeout when she calms down.
   The other really, really important thing is to show her how to express herself when she is upset.  If you can give her other ways of communicating that are more effective (especially, if you are ignoring her old ways), you will see a difference.
   Good Luck