Question

Let X and Y be the following sets: X = {5.6, 10, 12, 15, 18} Y = {6.10, 12, 15} What is the set X U Y?

Answer 1

Answer:

X U Y = {5.6, 10, 12, 15, 18}

Explanation:

Given the sets X and Y defined below:

$\begin{gathered} X=\mleft\{5.6,10,12,15,18\mright\} \\ Y=\mleft\{6.10,12,15\mright\} \end{gathered}$

The set X U Y is the union (joining) of the two sets without repeating any element.

Therefore:

$X\cup Y=\mleft\{5.6,10,12,15,18\mright\}$

Observe that all the elements of Y are in X.

$\begin{gathered} Y\subset X \\ \implies X\cup Y=X \end{gathered}$