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.