LaTeX markup suggested format: $\{y\in N_1 | y\le 4 \land (\exists x\in Z| x< 4 \land 6=yx\}$
Author's original post: {y:∈ N1 | y ≤ 4 Ʌ (∃x:∈Z | x < 4 . 6=y*x)}
The first part of the equation states that y is a natural number except zero and it is less than or equal to 4. $N_1$ is all natural numbers except zero. $y \le 4$ means that $y = 1, 2, 3, 4$
The second part of the equation after the AND ($\land$) states: there exists ($\exists$) a variable $x$ that is an integer (Z) such that $x$ is less than 4, which include: (...-2, -1, 0, 1, 2, 3)
The final calculation 6 = y * x yields the following combinations:
y x Truth Value 1 6 F (since x must be less than 4) 2 3 T 3 2 T 4 1.5 F (since x is not an integer)
No negative numbers in the set of $x$ need to be evaluated since the value must be 6 and $y$ cannot be negative. Therefore, I believe the set enumeration is: $\{2, 3\}$ However, the book says that the answer is $\{1, 2, 3\}$.
Please tell me if I'm right or the book is right.