The notation for the limit above is read as "The limit of formula_1 as formula_3 approaches formula_4 is formula_2", or alternatively, formula_10 as formula_11 (reads "formula_1 tends to formula_2 as formula_3 tends to formula_4"). Informally, this means that we can make formula_1 as close to formula_2 as possible—by making formula_3 sufficiently close to formula_4 from both sides (without making formula_3 equal to formula_4).