y=(1/2)*x^(2)*e^(x), x0 = 0
y``=(x+(1/2)x^2)`*e^(x)+(x+(1/2)x^2)*(e^(x))`=(1+x)*e^(x)+(x+(1/2)x^2)*e^(x)=(1+2x+(1/2)x^2)*e^(x)
y```=(1+2x+(1/2)x^2)`*e^(x)+(1+2x+(1/2)x^2)*(e^(x))`=(2+x+1+2x+(1/2)x^2)*e^(x)=(3+3x+(1/2)x^2)*e^(x)
y```(0)=3