Questions & Answers about Цена этих джинсов низкая.
Why is джинсов in the genitive plural and not in the nominative?
Because the word цена (“price”) answers the question цена чего? (“price of what?”). In Russian, that “of what” construction always takes the genitive case. Since джинсы (“jeans”) is plural, you use the genitive plural form джинсов.
Why is этих used instead of эти before джинсов?
Demonstrative adjectives (like “these”) must agree with the noun they modify in case, number, and gender. Here джинсов is genitive plural, so этих is the genitive plural form of этот (“this/these”).
Why is низкая used instead of низкий?
Adjectives in predicate position agree with the subject. Цена is a feminine noun in the nominative singular, so the adjective низкий must take its feminine singular nominative form низкая.
Could I use the adverb низко instead of the adjective низкая?
No. Низко is an adverb, and adverbs modify verbs, adjectives, or other adverbs—not nouns. If you wanted a short-form adjective, you could say цена низка, but that’s formal or literary. The normal way is цена низкая.