Question

Se A =]-1, +∞ [ e B = ] -2, 2] então o conjunto B – A é o conjunto vazio?

Answer 1

$x\in B-A\iff x\in B\wedge x\notin A\\ \\ x\in B-A\iff x\in B\wedge x\in (\mathbb R -A)\\ \\ x\in B-A\iff x\in \;]-2,2]\wedge x\in \left(\mathbb R -\;]-1,+\infty[\,\right)\\ \\ x\in B-A\iff x\in \;]-2,2]\wedge x\in ]-\infty;-1]\\ \\ x\in B-A\iff x\in \;]-2,2]\;\cap\; ]-\infty;-1]\\ \\ \boxed{x\in B-A\iff x\in \;]-2,-1[}$