"The knife is good."
Translation:El cuchillo es bueno.
Bueno follows a word; buen is used before. As I understand it, they have the same meaning--just a quirk of the language. El cuchillo bueno = El buen cuchillo = The good knife.
I'm under the impression "bien" usually means "well" or "fine". So to say "El cuchillo es bien" = "The knife is fine" might be some thing you say after you accidentally drop the knife off a 100 foot cliff, recover it and find it in great shape. "Well" of "fine" is about health. "Good" is about character or a quality. A respected brand name quality knife is "good". This issue is clouded by the fact most of us use fine/well/good as synonyms. Who knows if Spanish does it the same informally as we do. But my experience on duolingo is use "bien" mainly for "well" or "fine".
bueno is an adjective, bien is an adverb. Here good is an attribute to cuchillo >> adjective >> bueno
I looked up "knife" on a translation program to check the spelling and it showed cuchilla (f), not cuchillo. Anyone else seen it represented as feminine?
Duolingo also accepts la cuchilla for "the kinfe," but it doesn't always work. It probably should work in this case. report it.
If this is true than my answer, "La cuchilla es buena" should have been correct.
El cuchillo está/es bueno
In this case those both are correct but they have a slight difference meaning
Es cuchillo está bueno means the knife is good conditions, it can be used, the knife works, for example: if you use this knife to cut a very very tough meat, perhaps the knife will cut it but with a tremendous difficult but it will cut it.(the knife works)
EL cuchillo es bueno = this means that the knife is skillful in its task ( to cut) so we will use this knife to cut the tough meat which was cut very difficultly with the other one(ESTá bueno). The result is that we cut it the meat very easily due to this knife that Es bueno ( quiza es bueno porque es más filoso que el cuchillo que ESTÁ bueno)