
求帮忙做一道高数题
2个回答
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let
u= x-t
du =-dt
t=0, u=x
t=x , u=0
∫(0->x) f(x-t) dt
=∫(x->0) f(u) (-du)
=∫(0->x) f(t) dt
f(x)
= x+∫(0->x) tf'(x-t) dt
= x-∫(0->x) tdf(x-t)
=x -[ tf(x-t) ]|(0->x) + ∫(0->x) f(x-t) dt
=x - xf(0) +∫(0->x) f(x-t) dt
=x - xf(0) +∫(0->x) f(t) dt (1)
两边求导
f'(x) = 1-f(0) + f(x)
f'(x) - f(x) = 1-f(0)
let
f(x)= Ae^(x) -[ 1-f(0) ]
from (1)
f(x) =x - xf(0) +∫(0->x) f(t) dt
f(0) = 0
f(x)= Ae^(x) -[ 1-f(0) ]
0= A -1
A= 1
ie
f(x) =e^(x) - 1
u= x-t
du =-dt
t=0, u=x
t=x , u=0
∫(0->x) f(x-t) dt
=∫(x->0) f(u) (-du)
=∫(0->x) f(t) dt
f(x)
= x+∫(0->x) tf'(x-t) dt
= x-∫(0->x) tdf(x-t)
=x -[ tf(x-t) ]|(0->x) + ∫(0->x) f(x-t) dt
=x - xf(0) +∫(0->x) f(x-t) dt
=x - xf(0) +∫(0->x) f(t) dt (1)
两边求导
f'(x) = 1-f(0) + f(x)
f'(x) - f(x) = 1-f(0)
let
f(x)= Ae^(x) -[ 1-f(0) ]
from (1)
f(x) =x - xf(0) +∫(0->x) f(t) dt
f(0) = 0
f(x)= Ae^(x) -[ 1-f(0) ]
0= A -1
A= 1
ie
f(x) =e^(x) - 1
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