noun
BAD : Mathematics are my favourite subject.
GOOD : Mathematics is my favourite subject.
◆◆◆
Mathematics (the subject) is an uncountable noun: 'Mathematics is compulsory. Even if you don't like it, you still have to take it.'
noun
BAD : Mathematics are my favourite subject.
GOOD : Mathematics is my favourite subject.
◆◆◆
Mathematics (the subject) is an uncountable noun: 'Mathematics is compulsory. Even if you don't like it, you still have to take it.'
Longman Common Errors English vocabulary. Английский словарь распространенных ошибок Longman. 2012