Why does it say that David conquered, and not that he struck?
Radak (Shmuel II, 8:4): He killed in war only until they were conquered. He captured the rest, and took from them redemption of their souls. This is like Targum Yonasan - he tied them in fetters until they redeemed themselves.
Why does it say here 1,000 chariots and 7,000 horsemen, and in Shmuel II, 8:4 it says 1,700 horsemen?
Radak: There it counts only the great officers in Hadad'ezer's camp. Here it counts all the horsemen, and also the chariots, which are not counted there 1 .
Malbim (here and Shmuel II, 8:4): There it says "Elef u'Sheva Me'os Parashim", i.e. 1,000 chariots and 700 head horsemen, each of whom was appointed over 10 horses. This is why they are counted together with the chariots (each chariot had multiple horses, i.e. seven 2 ). Here it counts every horse by itself, therefore it counts 1000 chariots by themselves, and 7,000 Parashim, i.e. horses. Similarly, in Shmuel II, 10:18, regarding Aram, it says 700 chariots, and below (19:18) it says 7,000, for the same reason.
Radak: There it counts the Ragli (infantry); they are not counted here. (In our texts, they are counted also here! ? PF)
If we correct the text like this, we can explain his calculation. Even though regarding Aram, there were 10 horses in each chariot, we find that the number varied; refer to Bereishis 41:43:1:4 and the note there. (PF)
What is the meaning of "va'Y'aker"?
Radak: It is to remove the horse's feet from the knee and below, so the enemy cannot use them for war.
Why was David Me'aker the horses?
Rashi - he could not keep [more than he needed from] them, due to "Lo Yarbeh Lo Susim 1 " (Devarim 17:16).
Radak: One may destroy something only if it damages, or it is Asur b'Hana'ah, or to blot out memory, e.g. of Amalek.
Radak: The Torah forbids keeping more horses than needed, lest Yisrael regularly go to Egypt, for the [best] horses are there.
Why did David keep 100 chariots?
'Rashi', Radak: This is what he needed. Rashi (Shmuel II, 8:4) - a chariot has four horses, like it says in Divrei ha'Yamim 2:1:17 that an [Egyptian] chariot sold for 600 silver pieces, and a horse for 150. 1
The cost of the wagon itself is paltry, and is ignored. Perhaps it was given for free, like sellers often give a discount to one who buys a certain quantity. (PF)
