Is the word matemática the same in Brazilian and European Portuguese?

Yes

The spelling, meaning, and grammatical function of "matemática" are identical in both Brazilian and Continental Portuguese. The only difference lies in pronunciation.

In Brazilian Portuguese, the vowels are more "open" and clearly articulated. Each syllable is pronounced with distinct, clear vowel sounds. In Continental Portuguese, there is a heavy phenomenon known as vowel reduction. Unstressed vowels (such as the 'e' in matemática) are often "swallowed," shortened, or pronounced with a much more closed, neutral sound, making the word sound more compressed to a Brazilian ear.

Brazilian Portuguese Examples

1. Eu adoro matemática. (I love math.)
2. A prova de matemática foi muito difícil. (The math test was very difficult.)
3. Ele é muito bom em matemática. (He is very good at math.)
4. Eu tenho aula de matemática agora. (I have math class now.)
5. Matemática é a minha matéria favorita. (Math is my favorite subject.)

Continental Portuguese Examples

1. Eu gosto de matemática. (I like math.)
2. O exame de matemática foi muito difícil. (The math exam was very difficult.)
3. Ele tem muita facilidade com a matemática. (He has a lot of ease with math.)
4. Tenho aula de matemática agora. (I have math class now.)
5. A matemática é a minha disciplina favorita. (Math is my favorite subject.)