原式=-1/2*∫d(-2x)/√(1-2x) =-1/2*∫(1-2x)^(-1/2)d(1-2x) =(-1/2)*[(1-2x)^(-1/2+1)]/(-1/2+1)+C =-[(1-2x)^(1/2)]+C =-√(1-2x)]+C
