4049.sagews

var('x')
sinc(x) = (3*x^2)
abc(x)=x*sin(x)
a=plot(sinc, (x, -2, 2))
b=plot(abc, (x, -2, 2))
show(a+b)

var('x')
abc(x)=x^2/(x^2+1)
b=plot(abc, (x, -2, 2))
show(b)