In algebra, the letter a along with various other letters of the alphabet is often used to denote a variable, with various conventional meanings in different areas of mathematics.
ɪn ˈældʒᵻbɹə, ðə lˈɛɾɚɹ ɐ ɐlˈɔŋ wɪð vˈɛɹiəs ˈʌðɚ lˈɛɾɚz ʌvðɪ ˈælfəbˌɛt ɪz ˈɔfən jˈuːzd tə dᵻnˈoʊt ɐ vˈɛɹɪəbəl, wɪð vˈɛɹiəs kənvˈɛnʃənəl mˈiːnɪŋz ɪn dˈɪfɹənt ˈɛɹiəz ʌv mˌæθɪmˈæɾɪks.