Arithmetic operators and regex
You haven't defined your language, but presumably
$$
L \cap [^*0+0](+0])^* = \{ [^n[0+0](+0])^n : n \geq 0 \},
$$
where I replaced parentheses with square brackets. The latter language is essentially $\{a^nb^n : n \ge 0 \}$ in disguise, and so isn't regular. It follows that $L$ isn't regular as well.