1. Both of the restaurants we went to were not expensive.
2. Both of the restaurants we went to were cheap.
3. Neither of the restaurants we went to was expensive.
I'd like to know whether the sentences have the same meaning or not. In negative sentences, can 'both' be used?
No, it's ambiguous. Even though the word "not" appears next to "expensive", it's possible to take this sentence as "The restaurants we went to were not both expensive", a word order that makes it clear the meaning is "one or the other might have been, but not both". You could use "not" with "inexpensive", as you do with "cheap" in #2.
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No, it's ambiguous. Even though the word "not" appears next to "expensive", it's possible to take this sentence as "The restaurants we went to were not both expensive", a word order that makes it clear the meaning is "one or the other might have been, but not both".
You could use "not" with "inexpensive", as you do with "cheap" in #2.