> 数学 >
设f(x)连续,则
d
dx
x0
tf(x2t2)dt
=(  )
A. xf(x2
B. -xf(x2
C. 2xf(x2
D. -2xf(x2
人气:193 ℃ 时间:2019-08-20 23:43:29
解答
令:u=x2-t2
则:dt2=-du;
d
dx
x0
tf(x2t2)dt
=
d
dx
x0
1
2
f(x2t2)dt2

=
d
dx
0x2
1
2
f(u)du

=
d
dx
x20
1
2
f(u)du

=
1
2
f(x2)2x
=xf(x2
故本题选:A.
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