Final answer:
The infinitive stem of 'salir' for future and conditional tenses is 'salir-', with future and conditional endings attached to this stem to form conjugations like 'saliré' for future and 'saliría' for conditional.
Step-by-step explanation:
The infinitive stem of the verb salir remains the same in the future and conditional tenses, which is salir-. The infinitive stem of 'salir' for future and conditional tenses is 'salir-', with future and conditional endings attached to this stem to form conjugations like 'saliré' for future and 'saliría' for conditional.
However, when conjugating for these tenses, we use the infinitive as the base and attach the corresponding future or conditional endings. For example, in the future tense, we might say saliré ('I will leave'), where -é is the future tense ending for 'yo'.
In the conditional, it would become saliría ('I would leave'), with -ía as the conditional ending for 'yo'. It's worth noting that all regular and irregular verbs use their infinitives as the stem for forming the future and conditional tenses in Spanish.