Question: What is the source that Hotza'ah is called a Melachah?

Answer #1 (R. Shmuel bar Nachman citing R. Yonason): "Va'Ytzav Moshe va'Ya'aviru Kol b'Machaneh Leimor Ish v'Ishah Al Ya'asu Od Melachah li'Terumas ha'Kodesh va'Yikalei ha'Am me'Havi'' - people refrained from taking from their houses (tents) to give to Gizbarim (in Reshus ha'Rabim, who were accepting donations for the Mishkan).

Remark (R. Chizkiyah citing R. Ila): We learn even about Hachnasah from [this verse]. Just like people refrained from taking from their houses to give to Gizbarim, the Gizbarim refrained from taking from their hands and entering them to the chamber.

Answer #2 (R. Chizkiyah citing R. Acha): We learn all of them (Hotza'ah and Hachnasah) from "v'Lo Sotzi'u Masa mi'Bateichem b'Yom ha'Shabbos v'Chol Melachah Lo Sa'asu.''

(R. Yosa citing R. Yochanan): One who entered half a Grogeres and took out half a Grogeres is liable.

Assertion: What R. Yochanan said is unlike R. Yosi [in the following Beraisa. Rather, it is like the first Tana].

(Beraisa): If one was Motzi half a Grogeres, and was Motzi [another] half Grogeres in one Helam, he is liable. In two He'elamos, he is exempt;

R. Yosi says, in one Helam in one Reshus, he is liable. In one Helam in two Reshuyos, or in two He'elamos in one Reshus, he is exempt.

It is difficult [to say that R. Yosi holds like R. Yochanan]. Hotza'ah and Hotza'ah [to different Reshuyos] do not join according to R. Yosi. All the more so Hachnasah and Hotza'ah do not join! This shows that what R. Yochanan said is unlike R. Yosi.

(R. Ila): [R. Yosi exempts] not only when two openings [of the Chatzer from which he was Motzi] open to two roads (each is a different Reshus ha'Rabim). Rather, it is even if they open to one road. (It is as if he was Motzi to two roads, and he is exempt.)

Question: Just like R. Yosi equates Reshuyos to He'elamos to exempt, so he should equate Reshuyos to He'elamos to obligate;

If one was Motzi a Grogeres through this opening, and a Grogeres through this opening in one Helam, is he liable twice?! (Surely he is not!)

Answer (R. Yudan): For Chiyuv, even R. Yosi agrees [that separate Reshuyos are not like separate He'elamos. Rather, separate] Reshuyos [are like] eating [within the time to eat] half-loaves. (We explained this like MEICHAL HA'MAYIM);

If he ate a half-k'Zayis in the time to eat this half-loaf, and a half-k'Zayis in the time to eat this half-loaf, is he not exempt?! (Surely they do not join to obligate him!)

If he ate several k'Zeisim in the time to eat several half-loaves in one Helam is he not liable only once?! (Likewise, separate Reshuyos divide one Shi'ur to exempt, but they do not divide multiple Shi'urim to obligate multiple Chata'os.)

Rabanan of Kisarin: Rather than comparing it to [eating] Chelev, compare it to [other Melachos of] Shabbos!

If he wove one thread in this garment and one thread in this garment, is he not exempt?! If he wove several threads in several garments in one Helam, is he not liable only once?