Question

微积分问题:∫f(x)dx=F(x)+C,则∫f(sin 3x) dsin 3x

Answer 1

∫ f(x) = F(x) + C

Let u = sin3x => du = d(sin3x),不需要化为3cos3x dx

So ∫ f(sin3x) d(sin3x),就是求f(sin3x)对sin3x的积分,相当于求f(u)对u的积分,理清概念便可

= ∫ f(u) du

= F(u) + C

= F(sin3x) + C'