帮解几道求导的题,f(x)= (e^-5x)Cos3xg(r)=r/根号（r^2+1)x^2+y^2=2x^2yy=e^
1个回答

1.积法则

=(e^-5x)'cos3x+e^-5x(cos3x)'

=e^-5x(-5)cos3x+e^-5x(-sin3x)(3)

=e^-5x(-5cos3x-3sin3x)

2.商法则

={r'根号（r^2+1)-r[根号（r^2+1)]'}/(根号（r^2+1))^2

=[根号（r^2+1)-r^2/根号（r^2+1)]/（r^2+1)

3.两边对x求导

2x+2y*y'=4xy+2x^2y'

y'=(4xy-2x)/(2y-2x^2)

=(2xy-x)/(y-x^2)

4.链式

y'=e^(x/cosx)(x/cosx)'

=e^(x/cosx)(x'cosx-x(cosx'))/cos^2 x

=e^(x/cosx)(cosx+xsinx)/cos^2 x

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