she is good at mathematics
"My mathematics is good" is correct out of the choices given, but a better sentence would be "I am good at mathematics".
greeks had found the word mathematics
It's correct to say that a person is good AT mathematics.
Mathematics is a noun.
Mathematics is a noun.
It is not bad to be good at mathematics. It is specifically good.
Yes, the word 'mathematics' is a noun, a common, uncountable, abstract noun; a word for a concept, a word for a thing.
There is no difference between the phrases, "good in" or "good at". If a person is good in Mathematics, they are also good at Mathematics.
both can be, it depends whether you use 'maths' to mean 'mathematics' (i.e. the subject), or maths class/lesson. you can't be good in mathematics (you should say you are good at mathematics), but you could be good in maths class/ in you maths lesson. Generally speaking, You would use: "I am good at math". "I am good in/at maths" would both be incorrect. There is no need to add the s at the end of the word "math", because math is already the general term for the different types of mathematics.
The word is 'mathematics'.
MATHEMATICS