Learn Hardcore Indonesian: Tujuan rapat dijelaskan pada awal presentasi. - The purpose of the meeting is explained at the beginning of the presentation.

di- ... -kan is a common passive circumfix on verbs that in active form use meN- ... -kan.
The patient/topic (Tujuan rapat) comes before the verb. Active counterpart: Pembicara menjelaskan tujuan rapat pada awal presentasi.

What is the grammatical subject here?

Tujuan rapat is the subject (the thing being explained). In Indonesian passives, the patient/theme typically functions as the subject.

How do I say the same idea in active voice?

Use menjelaskan and put the agent as the subject:

Pembicara menjelaskan tujuan rapat pada awal presentasi. You can replace pembicara with a suitable agent (e.g., ketua rapat, narasumber).

How do I explicitly state who did the explaining in the passive?

Add oleh + agent after the verb:

Tujuan rapat dijelaskan oleh pembicara pada awal presentasi. Agentless passives (as in the original) are very common when the agent is obvious or unimportant.

What is the root and what do the affixes in dijelaskan do?

Root: jelas (clear).
Active: menjelaskan = to explain, to make something clear (causative).
Passive: dijelaskan = to be explained / to be made clear (patient voice). The suffix -kan reflects the causative/resultative sense from the base jelas.

Could I use synonyms like diterangkan, dipaparkan, dijabarkan, or diperjelas? Any nuance differences?

Yes, with nuances:

diterangkan: explained (often interchangeable with dijelaskan).
dipaparkan: presented/laid out (presentation/reporting nuance).
dijabarkan: elaborated/spelled out in detail.
diperjelas: clarified, made clearer (implies removing ambiguity rather than full explanation). Choose based on what you want to emphasize.

Is pada awal presentasi the same as di awal presentasi?

Functionally yes; both are widely used.

pada awal presentasi: slightly more formal/neutral.
di awal presentasi: very common in speech and writing. Don’t confuse with kepada, which means “to/for (a person/recipient).”

Can I omit the preposition and just say awal presentasi?

Not in this slot. You need pada or di:

Can I move the time phrase to the front?

Yes. Word order is flexible for adverbials:

Tujuan rapat dijelaskan pada awal presentasi. (neutral)
Pada awal presentasi, tujuan rapat dijelaskan. (fronted time; slightly more formal)
Formal/written option: Pada awal presentasi dijelaskan tujuan rapat. (subject after verb; less common in speech)

Does the sentence specify tense? How can I show past completion?

Indonesian doesn’t mark tense morphologically. Context supplies time. To mark completion:

Tujuan rapat sudah/telah dijelaskan pada awal presentasi. (already/has been explained) Use sudah (colloquial/common) or telah (formal).

What exactly does Tujuan rapat mean structurally? Why not tujuan dari rapat?

Tujuan rapat is a noun–noun compound: head (tujuan “goals”) + modifier (rapat “meeting”). This is the most natural, concise form.
tujuan dari rapat is acceptable but wordier; use it if you need to clarify or when the modifier is long/complex. Otherwise prefer tujuan rapat.

How do I show definiteness like “the goals” vs “some goals”?

Indonesian lacks articles. Use context or add markers:

Definite: tujuannya or tujuan rapatnya (the meeting’s goals).
Indefinite/some: beberapa tujuan, sebagian tujuan. Often bare tujuan rapat is understood as definite from context.

How do I express plural “goals”?

Options:

Reduplication: tujuan-tujuan rapat (emphasizes plurality/formal).
Quantifiers: beberapa tujuan rapat, semua tujuan rapat. Note: tujuan can be understood as plural from context without marking.

Do I need yang anywhere here?

No. Yang introduces relative clauses. Adding it would change the structure:

Tujuan rapat yang dijelaskan pada awal presentasi … now needs a main clause after it (e.g., … sangat jelas.). The original sentence doesn’t require yang.

Is there a more colloquial way to say this?

Yes, depending on register:

Neutral active: Pembicara menjelaskan tujuan rapat di awal presentasi.
Very colloquial (Jakarta-style): Pembicara ngejelasin tujuan rapat di awal presentasi. (use only in informal speech)

Can I nominalize it with penjelasan?

Yes. Natural alternatives:

Penjelasan tentang tujuan rapat disampaikan pada awal presentasi.
Penjelasan tujuan rapat diberikan pada awal presentasi. These foreground the act of explanation as a noun (penjelasan).