高等数学(上册)习题答案_吴赣昌_人民大学出版社_高数_理工类(11)

高等数学(上册)习题答案_吴赣昌_人民大学出版社_高数_理工类

7

f(x)=x+x2

f(x)

1

{f[f(x)]}22

x+x2≥0 x2≥ x x∈R

R

2

2 2 2 2

f[f(x)]=f x+x = x+x + x+x =2x+x

1

{f[f(x)]}2=1(2x+x2)2=x+x222

8

f(x)=sinx

f( (x))=1 x2

(x)

f( (x))=sin( (x))=1 x2 (x)=arcsin(1 x2)+2kπ

(x)

1≤1 x2≤1

2≤x≤2