i think is right @dkaeae

i think my correct answear to this question is . ∀x [(italian(x) ∧ winWC(National))⇒happy(x)]

Because in this example give a question "Italians are happy if the Italian National team wins the world cup." an explanation why this formula are wrong. I mean that i need to proof in some way, and i think to costruct an equivalent formula from the original one, by a trasformation (so CNF)...but i m not sure this is right way for proof. thanks so much for answear, finally i got the point!

Yes i got the point @Raphael but this example are very basic. This fuction all already know, and i hope the user know that O(n) is < than O(n^2). But for other example, the graph are very bad way to understand trend of the functions. Thanks for this suggestion.

you simple apply $\int_{0}^{1} x = 1/2$. And after we apply the linearity on the expectation? Because i don't caught why after we simplify the expression for reach the $2E(x-1/2)^2$

Why in C calculation, the expectation became (x-1/2)(y-1/2) ? You take middle point in [0,1] ? thanks for you answer