Parentheses impact on the order of operation so of couse they can affect the answer.

Example:

(6+2)*5=8*5=40

6+2*5 = 6+10=16

Parentheses are kinda' like commas.......their use - or omission - can imply two radically different things. For instance, notice the difference in these two sentences.......

1)  Let's eat grandmother.

2)  Let's eat, grandmother.

See the difference????