What is the meaning of "Teitivi"?
Rashi: You adorn yourself to greet your adulterers. This is like Izevel "va'Teitev Es Roshah" (Melachim II, 9:30) in the Parshah of Yehu.
Radak: You fix your ways to seek love of the nations, e.g. "Mah Lach l'Derech Mitzrayim u'Mah Lach l'Derech Ashur" (verse 18). An expression of Hatavah can apply to evil, e.g. to strengthen the matter - "ha'Heitev Charah Lach" (Yonah 4:4), "Ki Yeitiv El Avi Es ha'Ra'ah Alecha" (Shmuel I, 20:13), "Al ha'Ra Kapayim Leheitiv" (Michah 7:3).
Malbim: This verse addresses the group (refer to 2:31:1:2) that wants to serve Hashem better; they made up new Mitzvos, so Hashem will love them more. Do you think to be better than your fathers?!
Why does it say "Lachen"?
Rashi: This is an expression of a Shevu'ah.
Why does it say "Gam"?
Rashi: This means 'even'.
Malbim: Also the bad that you learned from the nations, you join it to the Torah, as if this will improve your way.
What is the meaning of "Es ha'Ra'os Limadt"?
Rashi: You taught (accustomed) yourself to act in the worst of all ways.
Radak: You taught the bad nations your evil ways.
Malbim: You adopted matters that you learned from the nations. E.g. Achaz built a Mizbe'ach in the Beis ha'Mikdash like what he saw in Damesek, as if he wants to improve the Mizbe'ach, or the Bamos that they built to increase Avodah. Really, this is opposite of Hashem's word!
Why is it written Limadti, and we pronounce it Limadt?
Radak: The Kesiv means that I taught you that your ways are evil, and evil will come to you due to them.
