Math Problem Statement

C and D are sets of real numbers defined as follows: C = {z | z ≥ 2}, D = {z | z ≤ 5}. Write C ∪ D and C ∩ D using interval notation. If the set is empty, write ∅.

Solution

Let's analyze the problem from the image you provided. Here's the information from the problem:

  • The set CC is defined as C={zz2}C = \{ z \mid z \geq 2 \}, meaning it includes all real numbers greater than or equal to 2.
  • The set DD is defined as D={zz5}D = \{ z \mid z \leq 5 \}, meaning it includes all real numbers less than or equal to 5.

Union of CC and DD ( CDC \cup D )

The union of two sets CDC \cup D includes all elements that are in either set CC or set DD, or in both.

  • CC is all real numbers greater than or equal to 2, so it is the interval [2,)[2, \infty).
  • DD is all real numbers less than or equal to 5, so it is the interval (,5](-\infty, 5].

Thus, the union of these two sets will cover all real numbers because there is overlap between CC and DD. So, CD=(,)C \cup D = (-\infty, \infty), which includes all real numbers.

Intersection of CC and DD ( CDC \cap D )

The intersection of two sets CDC \cap D includes only the elements that are in both sets CC and DD.

  • CC is [2,)[2, \infty), so it only includes numbers starting from 2.
  • DD is (,5](-\infty, 5], so it only includes numbers up to 5.

The overlap between these two sets is the interval from 2 to 5. Therefore, CD=[2,5]C \cap D = [2, 5].

Final Answer:

  • CD=(,)C \cup D = (-\infty, \infty)
  • CD=[2,5]C \cap D = [2, 5]

Let me know if you'd like further details or clarifications!

Here are 5 related questions for practice:

  1. What is the union of (,0)(-\infty, 0) and [3,)[3, \infty)?
  2. How do you find the intersection of (2,4](-2, 4] and [0,)[0, \infty)?
  3. What does the intersection of (,3](-\infty, -3] and (0,5)(0, 5) look like?
  4. If A=[0,3]A = [0, 3] and B=[2,6]B = [2, 6], what is ABA \cap B?
  5. What is the union of [0,1][0, 1] and [2,3][2, 3]?

Tip: When finding intersections, focus on the common overlapping range between the sets.

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Math Problem Analysis

Mathematical Concepts

Set Theory
Union of Sets
Intersection of Sets
Interval Notation

Formulas

C ∪ D = {x | x ∈ C or x ∈ D}
C ∩ D = {x | x ∈ C and x ∈ D}

Theorems

Union and Intersection Theorem

Suitable Grade Level

Grades 9-11