I would like to know if anybody from this forum have some insights about how to handle this demonstration:

"Show that for any discrete random variable X, e^{tE[X]}<= E[e^{tX}], where t is fixed and belongs to R." (E is expected value)

Maybe this is related with Jansen inequality, but certainly I'm not good regarding demonstrations.

By the way how can I learn the way of posting formulas in the forum?

Regards.