题目

Ever since I graduated from high school I've worked in the factories surrounding my hometown every summer. However, making the transformation between school and full-time blue-collar work during the break never gets any easier. For a student like me who considers any class before noon to be unacceptable, getting to a factory by 6 o'clock each morning is suffering. My friends never seem to understand why I'm so relieved to be back at school or that my summer vacation has been anything but a vacation.There are few people as self-confident as a college student who has never been out in the real w化简下列各式：（1）(-a2b)•(-b2a)3÷(-ba)（2）2aa2-4+12-a（3）先化简，再求值：xx-1-x+3x2-1•x2+2x+1x+3，其中x=2+1．