∫ x/√(1-x²)*e^[-√(1-x²)] dx = 1/2*∫ 1/√(1-x²)*e^[-√(1-x²)] dx²= -1/2*∫ [(1-x²)^(-1/2)]*e^[-√(1-x²)] d(1-x²)= -1*∫ e^[-√(1-x²)] d[√(1-x²)]= ...