第2个回答 2023-03-16
要求解函数$f(x) = x \sin(x^2)$的导数,我们可以使用乘法法则和链式法则。首先,使用乘法法则,将$f(x)$拆分为两个函数的乘积:
�
(
�
)
=
�
⋅
sin
(
�
2
)
f(x)=x⋅sin(x
2
)
然后,对于第一个函数$x$,它的导数是$1$,因此我们只需要对第二个函数$\sin(x^2)$求导。使用链式法则,我们令$u(x) = x^2$,则有:
�
�
�
sin
(
�
2
)
=
�
�
�
sin
(
�
)
⋅
�
�
�
�
=
cos
(
�
2
)
⋅
�
�
�
(
�
2
)
=
2
�
cos
(
�
2
)
dx
d
sin(x
2
)=
du
d
sin(u)⋅
dx
du
=cos(x
2
)⋅
dx
d
(x
2
)=2xcos(x
2
)
将这个结果代入乘法法则,我们得到:
�
�
�
(
�
sin
(
�
2
)
)
=
sin
(
�
2
)
+
�
⋅
2
�
cos
(
�
2
)
=
sin
(
�
2
)
+
2
�
2
cos
(
�
2
)
dx
d
(xsin(x
2
))=sin(x
2
)+x⋅2xcos(x
2
)=sin(x
2
)+2x
2
cos(x
2
)
因此,$f(x)$的导数是$\sin(x^2) + 2x^2 \cos(x^2)$。