x^4./根号下(1-x^2)^3不定积分
1个回答

令x=sinu,则:u=arcsinx,dx=cosudu.

∴∫{x^4/√[(1-x^2)^3]}dx

=∫[(sinu)^4/(cosu)^3]cosudu

=∫{[1-(cosu)^2]^2/(cosu)^2}du

=∫[1/(cosu)^2]du-2∫du+∫(cosu)^2du

=tanu-2u+(1/2)∫(1+cos2u)du

=tanu-2u+(1/2)∫du+(1/4)∫cos2ud(2u)

=sinu/cosu-(1/2)arcsinx+(1/4)sin2u+C

=x/√(1-x^2)-(1/2)arcsinx+(1/2)sinucosu+C

=x/√(1-x^2)-(1/2)arcsinx+(1/2)x√(1-x^2)+C.