If I quit and tap into my 401 k to go to school what would my penalities be on 34000 with 2 dependents?

First it would help if you read instructions. I'm curious as to why you ignored the bold, red, Read First instructions and when ahead and posted under Forum Help (I've moved this to an approprate forum).

Assuming you are not eligible for a hardship withdrawal, you would lose $3400 as the withdrawal penalty. And you would have to pay taxes on the $34K What that would be depends on your tax filing.

You would be MUCH better off either taking a loan against your 401K or even taking a student loan.

Agreed; the penalty and taxes will kill you if you access the 401K prematurely.