Floor or Greatest Integer Function

Algebra-1

1. Fundamental Concepts

  • Definition: The floor function, denoted as $$\text{{floor}}(x)$$ or $$\lfloor x \rfloor$$, is a function that returns the greatest integer less than or equal to $$x$$. For example, $$\lfloor 3.7 \rfloor = 3$$ and $$\lfloor -2.3 \rfloor = -3$$.
  • Graphical Representation: The graph of the floor function consists of horizontal line segments with jumps at integer values.
  • Properties: The floor function is not continuous at integer points and has a step-like appearance.

2. Key Concepts

Evaluation Rule: $$\lfloor x \rfloor = n \quad \text{if} \quad n \leq x < n+1$$
Application: Used in various fields including computer science, number theory, and discrete mathematics.
Identities: $$\lfloor x + n \rfloor = \lfloor x \rfloor + n$$ for any integer $$n$$

3. Examples

Example 1 (Basic)

Problem: Evaluate $$\lfloor 4.5 \rfloor$$

Step-by-Step Solution:

  1. The greatest integer less than or equal to 4.5 is 4.
  2. Therefore, $$\lfloor 4.5 \rfloor = 4$$.
Validation: Since 4 ≤ 4.5 < 5, the solution is correct.

Example 2 (Intermediate)

Problem: Evaluate $$\lfloor -3.2 \rfloor$$

Step-by-Step Solution:

  1. The greatest integer less than or equal to -3.2 is -4.
  2. Therefore, $$\lfloor -3.2 \rfloor = -4$$.
Validation: Since -4 ≤ -3.2 < -3, the solution is correct.

4. Problem-Solving Techniques

  • Visual Strategy: Use a number line to visualize the position of the number and identify the greatest integer less than or equal to it.
  • Error-Proofing: Always check if your answer satisfies the condition $$n \leq x < n+1$$.
  • Concept Reinforcement: Practice with a variety of numbers, both positive and negative, to solidify understanding.