Math Problem Statement

Consider the following equation involving a ceiling function:

[

\left\Iceil 2x - 1 \right\rceil + \left\Iceil x + 3 \right\rceil = 12

]

Find all real numbers (x) that satisfy this equation.

Solution

To solve the equation involving the ceiling function:

2x1+x+3=12\left\lceil 2x - 1 \right\rceil + \left\lceil x + 3 \right\rceil = 12

we need to understand how the ceiling function \lceil \cdot \rceil works. The ceiling function y\lceil y \rceil gives the smallest integer greater than or equal to yy.

Let's denote: 2x1=a\left\lceil 2x - 1 \right\rceil = a x+3=b\left\lceil x + 3 \right\rceil = b

where aa and bb are integers, and we know that: a+b=12a + b = 12

Analyzing 2x1=a\left\lceil 2x - 1 \right\rceil = a:

a1<2x1aa - 1 < 2x - 1 \leq a a<2xa+1a < 2x \leq a + 1 a2<xa+12\frac{a}{2} < x \leq \frac{a + 1}{2}

Analyzing x+3=b\left\lceil x + 3 \right\rceil = b:

b1<x+3bb - 1 < x + 3 \leq b b4<xb3b - 4 < x \leq b - 3

Solving the Combined Inequalities:

We need xx to satisfy both sets of inequalities simultaneously.

Given a+b=12a + b = 12, let's substitute b=12ab = 12 - a:

  1. For 2x1=a\left\lceil 2x - 1 \right\rceil = a: a2<xa+12\frac{a}{2} < x \leq \frac{a + 1}{2}

  2. For x+3=12a\left\lceil x + 3 \right\rceil = 12 - a: 11a<x12a11 - a < x \leq 12 - a

Therefore, we need to find aa such that the intervals: a2<xa+12\frac{a}{2} < x \leq \frac{a + 1}{2} and 11a<x12a11 - a < x \leq 12 - a

Finding the Overlapping Intervals:

To find a common xx that fits both intervals:

  1. a2<12a\frac{a}{2} < 12 - a
  2. 11aa+1211 - a \leq \frac{a + 1}{2}

Solving a2<12a\frac{a}{2} < 12 - a:

a<242aa < 24 - 2a 3a<243a < 24 a<8a < 8

Solving 11aa+1211 - a \leq \frac{a + 1}{2}:

222aa+122 - 2a \leq a + 1 213a21 \leq 3a 7a7 \leq a

Thus, aa must be an integer such that: 7a<87 \leq a < 8

This means a=7a = 7.

Verifying a=7a = 7 and Finding xx:

For a=7a = 7: 72<x82\frac{7}{2} < x \leq \frac{8}{2} 3.5<x43.5 < x \leq 4

And for b=5b = 5 (since b=12a=127=5b = 12 - a = 12 - 7 = 5): 117<x12711 - 7 < x \leq 12 - 7 4<x54 < x \leq 5

The intervals do not overlap since 3.5<x43.5 < x \leq 4 and 4<x54 < x \leq 5 are disjoint.

Thus, there are no real numbers xx that satisfy the given equation.

Conclusion:

There are no real numbers xx that satisfy the equation 2x1+x+3=12\left\lceil 2x - 1 \right\rceil + \left\lceil x + 3 \right\rceil = 12.

Would you like more details on the analysis or have any other questions?

Here are some related questions to expand on this topic:

  1. What are the properties of the ceiling function?
  2. How do the ceiling and floor functions differ?
  3. Can ceiling functions ever produce non-integer values?
  4. How would the solution change if we replaced the ceiling functions with floor functions?
  5. What real-world applications make use of ceiling functions?

Tip: When dealing with piecewise functions like the ceiling function, always consider the intervals where the function changes value to identify possible solutions.

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Math Problem Analysis

Mathematical Concepts

Algebra
Ceiling Function
Piecewise Functions

Formulas

Ceiling Function: ⌈y⌉ gives the smallest integer greater than or equal to y

Theorems

Properties of Ceiling Functions

Suitable Grade Level

Grades 10-12