Question

y=xcosx在x=

π

3

处的导数值是______．

Answer 1

y′=x′cosx+x（cosx）′=cosx-xsinx
所以y=xcosx在x=

π

3

处的导数值是cos

π

3

-

π

3

sin

π

3

=

1

2

-

3 π

6

故答案为

1

2

-

3 π

6