Question

the union of the sets (closed intervals) A=[3,6] and B=[4,8.5] is
a. [3,8.5]
b. [4,6]
c. [3,6]
d. [3,4]

Answer 1

a.[3,8.5]

Answer 2

why?

Answer 3

common element in sets are written once in union

Answer 4

hmmm what does that mean?

Answer 5

If you have a set, call it A, and another set B.
Then:
\[A \cup B\]
Is all the units of both!
So if A={1,2} and B={3,7}
\[A \cup B = \left\{1,2,3,7 \right\}\]

Answer 6

but how did he get [3,8.5]???

Answer 7

Because its an interval.
You have
3-4-6--8.5
If you take 3,6 and combine it with 4,8.5.
You don't need to repeat the 4 to whatever because its already included in the bigger interval. So you only need [3,8.5]

Answer 8

ohhh gotcha!!!