Question

Please help! write D u E and D n E using interval notation.

Answer 1

Part 1

`D \cup E` denotes the union of the two sets (in other words, all the elements in both sets).

This means it is
`(-\infty, 4) \cup [7, \infty)`

Part 2

`D \cap E` denotes the elements shared between both sets.

This means the answer is
`(4, 7]`