This just came up in my head.

We use "has" for HE SHE IT (third person singular).
"he has 3 cars."

But when it is in a negative sentence:
"he didn't have three cars"

Is it correct to use have instead of has?
Anonymouswhich is correct use have instead of has

Your question is very broad.

He has

She has

It has

Third person present tense of "to have."

Do you have more specific questions than that?
The main verb in the sentence is "do". Do + infinitive makes an intensive or interrogative mood of the second verb (have)

He does have a car.
Does he have a car?
He did have a car.
Did he have a car?
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Your negative sentence is in the past tense, Melanie, where the third person singular inflection does not appear.

He doesn't have three cars'-- it is the operator ('do' here) which takes the '-s' inflection.
which is correct use have instead of has
 BarbaraPA's reply was promoted to an answer.
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 AlpheccaStars's reply was promoted to an answer.
Only one s-marker or d-marker per clause!
See Have or has.

Which is right?

He has a car, or

He have a car.

The sentence formation is not a question statement.

It is an information for some one to say.

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