[答案] S1-S2+S3
[合 作 探 究·攻 重 难]
求简单函数的定积分
求下列定积分.
(1)(2x+ex)dx;
(2)dx;
(3) 2dx;
(4)(x-3)(x-4)dx.
[解] (1)(2x+ex)dx=(x2+ex) =(1+e1)-(0+e0)=e.
(2)dx
=(ln x-3sin x)
=(ln 2-3sin 2)-(ln 1-3sin 1)
=ln 2-3sin 2+3sin 1.
(3)∵2
=1-2sin cos =1-sin x,
=-(0+cos 0)=-1.