1.y=xe^(-x²)
=>
y'=e^(-x²)+xe^(-x²)*[-2x)=(1-2x²)e^(-x²)
2.y=2x³/(x²-4)
=>y'=[6x²(x²-4)-2x³(2x)]/(x²-4)²=2x²(x²-12)/(x²-4)²