Learn German: Gehen Sie in das Schlafzimmer hinauf!

The prefix hin shows movement away from the speaker, while her shows movement towards the speaker. Since the speaker is telling the listener to go up into the bedroom, the speaker must be downstairs. The listener is moving away from them, so they use hinauf (up and away) instead of herauf (up and towards).

Is hinaufgehen a separable verb?

Yes! hinaufgehen (to go up) is a separable verb. In a command like this, the prefix hinauf splits off and goes to the very end of the sentence, while the core verb Gehen takes the first position.

Why is it in das Schlafzimmer instead of in dem Schlafzimmer?

The preposition in is a two-way preposition. Because the person is moving to a destination (going into the bedroom), it takes the accusative case (das). If they were already doing an activity inside the bedroom, it would take the dative case (dem).

Can I shorten in das to ins in this sentence?

Yes, it is very common in everyday German to combine in das into ins. The sentence would then be: Gehen Sie ins Schlafzimmer hinauf!