y=arcsinx/√(1-x^2)
y'=[(arcsinx)'√(1-x^2)-arcsinx*(√(1-x^2))']/(1-x^2)
=[1+arcsinx* x/√(1-x^2)]/(1-x^2)
=1/(1-x^2)+xarcsinx *(1-x^2)^(-3/2)
y"=2x/(1-x^2)+(arcsinx+x/√(1-x^2))*(1-x^2)^(-3/2)+xarcsinx*(-3/2)*(1-x^2)^(-5/2)* (-2x)
=2x/(1-x^2)+[arcsinx+x/√(1-x^2)]*(1-x^2)^(-3/2)+6x^2arcsinx*(1-x^2)^(-5/2)这一步y'=[(arcsinx)'√(1-x^2)-arcsinx*(√(1-x^2))']/(1-x^2）不是应当是 y'=[(arcsinx)'√(1-x^2)-arcsinx*(√(1-x^2))']/(1-x^2)^2分母应该是√(1-x^2) 的平方呀