$5.(2$ points$)$ Prove that the following problem is NP$-$complete: given a graph $\backslash ($ G $\backslash )$ with $\backslash (3$ n $\backslash )$ vertices, determine whether $\backslash ($ G $\backslash )$ has a clique of $\backslash ($ n $\backslash )$ vertices.

$6.(2$ points$)$ Suppose $\backslash (\backslash$mathrm$\{$P$\}$

eq $\backslash$mathrm$\{$NP$\}\backslash ).$ Could there exist a polynomial$-$time algorithm which, being given a Boolean formula $\backslash (\backslash$varphi $\backslash ),$ answers whether the number of satisfying assignments for $\backslash (\backslash$varphi $\backslash )$ is less or equal than $2?$