shirazu, wakarazu?

[Yamatoblue]

How do we conjugate verbs into the negative with the "zu" at the end?
Like shirazu (dont know,etc).
How does one conjugate these and when are they used?
Are they an informal form or formal form?

Thanks! :wave:

[GaijinPunch]

They're similar to the ~naide form. (Not the commanding form, but the other one).
I'm not exactly sure what you're asking. You've conjugated it correctly (w/ shirazu).
Something to note is that something is supposed to follow this form. If it doesn't, it's inferred.
It's pretty formal.

a sezu ni b wo suru.
Did b without doing a.

[Yamatoblue]

Well i dont know how to conjugate it. Could you please help me?
Shirazu I know b/c I've seen it many times. How about other verbs?
What is the rule to conjugating it to this form?

[McCrutch67]

It's just as GaijinPunch said, like the nai form.
Do you know shiru->shiranai?

It's the same but with shira -zu instead of shira -nai. The final -u becomes -azu.

Of course type 1 verbs will replace the -ru with -zu instead. GaijinPunch already told the formality and how it's used.