求不定积分:∫xcos(4x^2 +5)dx

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求不定积分:∫xcos(4x^2+5)dx求不定积分:∫xcos(4x^2+5)dx求不定积分:∫xcos(4x^2+5)dx∫xcos(4x^2+5)dxlet4x^2+5=tdt=d(4x^2+5

求不定积分:∫xcos(4x^2 +5)dx
求不定积分:∫xcos(4x^2 +5)dx

求不定积分:∫xcos(4x^2 +5)dx
∫xcos(4x^2 +5)dx
let 4x^2+5=t
dt=d(4x^2+5)=4d(x^2)=4*2xdx=8xdx so dx=[dt/8x]
∫xcos(4x^2 +5)dx=∫xcostdt/8x=1/8∫costdt=1/8sint
=1/8(4x^2+5)
写了这么久,竟然没有悬赏分?...

∫xcos(4x^2 +5)dx=1/2∫cos(4x^2 +5)dx^2=1/8∫cos(4x^2 +5)d(4x^2 +5)
=-1/8sin(4x^2 +5)+c

∫xcos(4x^2 +5)dx=1/2∫cos(4x^2 +5)dx^2=1/8∫cos(4x^2 +5)d(4x^2 +5)
=1/8sin(4x^2 +5)+c