d∫(t³+t)dt/dx(上限为x,下限为0)
=x³+x
∫cos√(x+1)dx
令√(x+1)=t,那么x=t²-1
=∫costd(t²-1)
=2∫tcostdt
=2∫td(sint)
=2(tsint-∫sintdt)
=2tsint+2cost
=2√(x+1)sin√(x+1)+2cos√(x+1)