f(x)=x
f(x)=sen(x)
f(x)=(5)^x
f(x)=k
f(x)=3x-2
f(x)=3cos(x)
f(x)=-2
f(x)=e^3x
f(x)=x^2-3x+2
f(x)=x/(x+2)
f(x)=log (x)
f(x)=2/3 tan(2x)
