Question
Which of the following is an empty set?
A) The set of prime numbers which are even.
B) The solution set of the equation $\frac{2(2x+3)}{x+1}-\frac{2}{x+1}+3=0,x\in\mathbb R$
C) $(A\times B)\cap(B\times A),$ where A and B are disjoint.
D) The set of reals which satisfy $x^2+ix+i-1=0$
(The answer given is C))
My Attempt:
I think the answer should be B), C), D).
Regarding option B)
$$\frac{4x+6-2}{x+1}+3=0\\4+3=0$$
Regarding D)
$x=\frac{-i\pm\sqrt{-1-4i+4}}2$
Please confirm.
A) is obviously nonempty since $2$ is in the set.
B) $x=-1$ is clearly not acceptable as a solution, since the equation is not defined at $x=-1$. Now assuming $x\neq-1$. Then we get $7x=-7$ which gives $x=-1$, contradiction. Therefore here we have an empty set.
C)If we assume that there is an $(a,b)$ in $(AXB)\bigcap(BXA)$ then $(a,b)$ is in $AXB$ and in $(BXA)$ i.e $a$ is in $A$ and $B$, contradiction. Here the set is empty
D)The set is nonempty since for $x=-1$ the equation is satisfied!
So I only disagree with the answer in (B)!!