Recently, I have picked up a Quantum Computing class. We have been asked to find the expectation value of $X$ tensor $Z$ and $H$ tensor $H$
$$ (|00>+|11>)/\sqrt(2); \qquad (|00>-|11>)/\sqrt(2); \qquad(|01>+|10>)/\sqrt(2); \qquad(|01>-|10>)/\sqrt(2); $$
I have found some stuff on the expectation value and it looks like a big integral that I have not yet learned about. I know the expected value from Probability, but I am pretty sure I am looking at different things. If someone could guide me or direct me to a place that first explains what is the expectation value and then how to apply the operator tensor operator to the basis states, that would be great. I am comfortable working in vectors for most of these problems. Thank you.