It is perfectly legal to carry that particular knife in both Los Angeles county and city as long as you carry it concealed. There is no blade length limit on folders as long as they are carried concealed (except switchblades and butterfly knives). It might seem counter to the nonsensical logic that often goes into restrictive knife laws that the law would require such knives to be carried concealed rather than openly and visible, but that's the way they wrote the laws.
Both Los Angeles county and city (municipality) have a blade length limit of 3" for ALL knives carried openly. Any knives carried in a visible manner must have blades no longer than 3" long. There are exceptions to that limit however- like if you are carrying the knife for "legitimate" work-related reasons, or for outdoor activities (hiking/fishing/camping/etc), or for purposes of religious worship (no length limit for all those reasons). But if someone is going to claim one of those exceptions they had better be prepared to prove it.
Also, carrying that knife with any portion visible (like carrying it clipped inside your pocket) might constitute "open carry" due to part of it being visible.
It's highly unlikely that you would ever be stopped, hassled, or arrested by an LEO for carrying such a knife in a visible manner, but I say- why take the chance. It's easy enough to carry such a knife concealed and avoid the unpleasantness of being arrested or detained.
