y = xe^(x²)y' = e^(x²)+2x²e^x² = (1+2x²)e^x²y'' = (1+2x²)' e^x² + (1+2x²)(e^x²)'= 4xe^(x²) + (1+2x²)2xe^(x²)= 2x(3+2x²) e^(x²)
就按照乘法的导数去求啊
