If you want a slang term meaning you brilliantly succeed, you might say:

J’ai cartonné à mon examen.

This comes from “faire un carton” like at a shooting range in a fair.

Bâcler quelque chose means to do something sloppily, without giving it the required level of attention. In someone else’s mouth, it’s often a criticism implying shoddy results but the primary meaning is related to the level of effort, not the quality of the result.

To refer to the poor result for an exam, in the high register of speech you would say échouer, and in everyday language you would typically use planter, se planter, rater as in:

J’ai échoué à l’examen

J’ai planté mon bac

Je me suis planté dans la deuxième partie de l’examen

J’ai raté mon permis [driver’s license exam]

For the particular case of an entrance exam you can also say être recalé.

To say the opposite, in the high register of speech you would say réussir. Popular antonyms to describe success would be torcher, cartonner, assurer, déchirer.

J’ai torché le bac

J’ai cartonné à l’épreuve orale

J’ai trop bien assuré dans la deuxième partie

J’ai déchiré les maths

These last four terms are slang, but torcher is borderline vulgar: the literal meaning is to wipe one’s ass, the image behind this being that of someone blazing through the exam as if were toilet paper.

Some slang terms in use by scientific students:

• majorer for "coming in with the highest score" (J’ai majoré l’épreuve de physique du concours)
• trivialiser for "doing well and making it look easy"

(Thanks Random for déchirer !)

“J’ai géré” is often my favorite translation for “I nailed it”.

Note that in “J’ai géré”, there is no reference to “examen” (the it in “I nailed it”). It would be “Je l’ai géré”, you can say that but it’s often omitted.

Don’t forget that “gérer” means “to manage”, “to run”, “to handle”, so of course it’s not slang in some contexts.

Slang example :

• Salut mec, t’as apporté de la bière ?
• Ouais ! J’en ai apporté cinq packs !
• Ouah ! T’as géré ! (or “Ouah ! Tu gères !”)

Other example :

• Comment s’est passé ton examen ?
• Hum, je pense que j’ai géré, mais on verra !

It might be scientific prépas slang, but we used “torcher” to describe exactly that: doing fast and well. Of course, when talking about a full-length exam, in prépas it meant actually completing the copy or at least getting near, but you could vary well torcher a single question or exercise.

en prenant le sens de bâcler = faire vite et mal,faire salement , le contraire est faire méticuleusement/sérieusement et bien.

• assurer
• peaufiner
• blinder (familier)

Les autres termes qui ne font pas référence à ce concept vite/pas vite ne répondent pas exactement à la question: échouer/réussir, rater, louper, …