Math Problem Statement

(x - 1)^2 ≥ 4

Solution

The problem presented is the polynomial inequality:

(x1)24(x - 1)^2 \geq 4

Step 1: Isolate the expression.

Start by solving the corresponding equality to find the critical points:

(x1)2=4(x - 1)^2 = 4

Take the square root of both sides:

x1=±2x - 1 = \pm 2

Thus, the two solutions are:

x=1+2=3orx=12=1x = 1 + 2 = 3 \quad \text{or} \quad x = 1 - 2 = -1

So the critical points are x=1x = -1 and x=3x = 3.

Step 2: Solve the inequality.

Now we solve the inequality:

(x1)24(x - 1)^2 \geq 4

This inequality is satisfied when (x1)2=4(x - 1)^2 = 4, which we already found as x=1x = -1 and x=3x = 3. Additionally, since (x1)2(x - 1)^2 represents a parabola opening upwards, it is greater than or equal to 4 outside the interval (1,3)(-1, 3). So, we test values in the intervals:

  1. For x<1x < -1 (e.g., x=2x = -2): (21)2=94(-2 - 1)^2 = 9 \geq 4 This is true, so x<1x < -1 satisfies the inequality.

  2. For 1<x<3-1 < x < 3 (e.g., x=0x = 0): (01)2=1≱4(0 - 1)^2 = 1 \not\geq 4 This is false, so the inequality does not hold in this interval.

  3. For x>3x > 3 (e.g., x=4x = 4): (41)2=94(4 - 1)^2 = 9 \geq 4 This is true, so x>3x > 3 satisfies the inequality.

Step 3: Interval notation.

The solution includes x=1x = -1 and x=3x = 3 because the inequality is "greater than or equal to." Therefore, the solution in interval notation is:

(,1][3,)(-\infty, -1] \cup [3, \infty)

This is the set of all xx values that satisfy the inequality.


Would you like further details or have any questions?

Here are some related questions to deepen understanding:

  1. How do you determine when to use a union of intervals in inequalities?
  2. What is the graphical representation of (x1)2=4(x - 1)^2 = 4?
  3. Why do we need to check each interval between critical points for inequalities?
  4. What happens if the inequality were strict, (x1)2>4(x - 1)^2 > 4?
  5. How do you solve inequalities with absolute values?

Tip: When solving polynomial inequalities, always solve the related equation first to find critical points and then check the intervals around those points.

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Math Problem Analysis

Mathematical Concepts

Algebra
Inequalities
Polynomials

Formulas

(x - 1)^2 = 4
Square Root Principle

Theorems

Inequality solving by critical points

Suitable Grade Level

Grades 9-10