1) Yesterday I bought 4 legs meeting table (incorrect) 2) Yesterday I bought a 4-leg meeting table (marginal) 3) Yesterday I bought a 4-legged meeting table (correct, but spell out the number)

3 is correct, but it might also be easier to say "Yesterday I bought a meeting table with 4 legs" or just "Yesterday I bought a meeting table" (4 legs is implied when you are talking about a table).

(1) and (2) are incorrect. (3) is absolutely fine. fueqan alam: I don't think we'd ever say "i was committed to buying" in this context. it's not incorrect English, but doesn't really portray the same meaning as "i bought", it would be more often used like: "I was committed to buying the table yesterday, but today I decided not to (buy it)"

IF you are obsessive with your English,you can say:I was committed to buying a four legged table,yesterday.''A'' is used with count nouns and as table is a count noun so you had better to implement the article "a",Have a nice day.BTW, the first two sentences aren't preferable and there's a mistake even in your question,we don't say :there has a mistake,(rectification):there's a mistake.