求这两题的不定积分
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求这两题的不定积分
求这两题的不定积分
求这两题的不定积分
(7)
∫ dx/[e^x+e^(-x)]
=∫ e^xdx/(e^2x+1).分子分母同时乘以e^x
=∫ d(e^x)/(e^x)^2+1
=arctan(e^x)+C
(10)
∫xcos(x²)dx
=∫cos(x²)(xdx)
=∫cos(x²)(d(x²)/2)
=(1/2)∫cos(x²)d(x^2)
=(1/2)sin(x²)+C