أُدْخِلُ (udxilu): This is a transitive (to enter) verb. It means (I enter) but either someone, or often used to entering data or some input into a machine or a computer.
أَدْخُلُ (adxulu): I enter, intransitive, meaning "I enter" , and used for regular passing through some door or getting into some space.
The diacritics (harakat) are somewhat small so I hope they are clear here
Not to do with this exercise, but may I express an opinion about transliteration? I have seen "x" used to transliterate the unvoiced velar fricative (eg خ in Arabic), and I assume that's because at least in a couple of language that sound is written as a form of cross (eg Russan, Greek). But in English, French, and probably other languages, "x" suggests the sounds "ks", so I don't see any advantage to it. Do you see some disadvantage to the conventional "kh" for this sound? I don't think it's ambiguous, is it?
and in Maltese and Catalan it represents the sound of (Sh) ش.
Well, as I've stated before in another thread, I try my best to keep phonemes represented with a single symbol as much as possible. As for (kh) things can get ambiguous when this sound comes with Shaddah, doubling; e.g. سَخَّرَ (to subjugate/to exploit/to implement). Using (KH), the transliteration for this verb would be (sakhkhara). I find it confusing that way, and might be better as (saxxara).