We've got

My old English teacher used to tell us off if we ever used the word got.

We have to invest....

We must invest.....

Thank you, but didn't understand exactly your answer and the role of "got".
Can you please explain more?

It is a colloquial American usage. One cannot say that it is either correct or incorrect. Contrary to popular opinion, English is not bound by hard and fast rules. A colloquy is a conversation, and colloquial usage means how the language is used in conversation. Among Americans, "have got" is a colloquial usage.

EDIT: You would be justified in viewing "have got" as redundant. Nevertheless, it is a common colloquial usage in the American language.

Yes, it's colloquial - but it's still wrong ;-) . You're adding an unnecessary word ('got') "you've got (have got) to be kidding" and "you have to be kidding" - say exactly the same thing.

Ain't ain't a word in english neither...don't mean it's right...

It's wrong? Did god die and leave you in charge? I know of no reason to consider you an authority on anything.

It's colloquial/conversational in British usage too.

I was unaware of that.

Practically universal in relaxed conversational speech, in all dialects from street to posh. At school we were told that "got" has no work to do in sentences like "I have got a new hat" but that ignored its use to signify relaxed tone and willingness to occupy the same social level as the listener.