Math Problem Statement

|x+1|-|2x-1|<1

Solution

To solve the inequality x+12x1<1|x+1| - |2x-1| < 1, we will need to consider different cases based on the expressions inside the absolute values. The critical points occur when the expressions inside the absolute values are zero, which are at x=1x = -1 and x=12x = \frac{1}{2}.

Step 1: Break the number line into intervals based on the critical points:

  • x<1x < -1
  • 1x<12-1 \leq x < \frac{1}{2}
  • x12x \geq \frac{1}{2}

Step 2: Solve the inequality on each interval.

Case 1: x<1x < -1

In this region, x+1x+1 is negative and 2x12x-1 is negative, so: x+1=(x+1)=x1|x+1| = -(x+1) = -x - 1 2x1=(2x1)=2x+1|2x-1| = -(2x-1) = -2x + 1 Substitute these into the inequality: (x+1)((2x1))<1-(x+1) - (-(2x-1)) < 1 Simplify: x1+2x1<1-x - 1 + 2x - 1 < 1 x2<1x - 2 < 1 x<3x < 3 In this case, x<3x < 3 must also satisfy x<1x < -1. Therefore, the solution in this region is x<1x < -1.

Case 2: 1x<12-1 \leq x < \frac{1}{2}

In this region, x+1x+1 is non-negative and 2x12x-1 is negative, so: x+1=x+1|x+1| = x+1 2x1=(2x1)=2x+1|2x-1| = -(2x-1) = -2x + 1 Substitute these into the inequality: (x+1)((2x1))<1(x+1) - (-(2x-1)) < 1 Simplify: x+1+2x1<1x + 1 + 2x - 1 < 1 3x<13x < 1 x<13x < \frac{1}{3} So, the solution in this region is 1x<13-1 \leq x < \frac{1}{3}.

Case 3: x12x \geq \frac{1}{2}

In this region, both x+1x+1 and 2x12x-1 are non-negative, so: x+1=x+1|x+1| = x+1 2x1=2x1|2x-1| = 2x-1 Substitute these into the inequality: (x+1)(2x1)<1(x+1) - (2x-1) < 1 Simplify: x+12x+1<1x + 1 - 2x + 1 < 1 x+2<1-x + 2 < 1 x<1-x < -1 x>1x > 1 Thus, the solution in this region is x>1x > 1.

Step 3: Combine all the solutions

  • For x<1x < -1, the solution is x<1x < -1.
  • For 1x<12-1 \leq x < \frac{1}{2}, the solution is 1x<13-1 \leq x < \frac{1}{3}.
  • For x12x \geq \frac{1}{2}, the solution is x>1x > 1.

Thus, the final solution is: x(,1)[1,13)(1,)x \in (-\infty, -1) \cup \left[ -1, \frac{1}{3} \right) \cup (1, \infty)

Would you like more details on any of these steps or a graph of the solution?

Here are some related questions you might find useful:

  1. How do absolute value functions impact inequalities?
  2. What is the general method for solving absolute value inequalities?
  3. How do critical points divide the number line in inequalities?
  4. Can you explain how to graph absolute value inequalities?
  5. What are some special cases when solving inequalities involving absolute values?

Tip: Always check for cases by breaking down absolute value inequalities into multiple intervals!

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Math Problem Analysis

Mathematical Concepts

Algebra
Absolute Value Inequalities
Piecewise Functions

Formulas

Absolute Value Definition: |x| = x if x >= 0, -x if x < 0
Inequality Solving: Break into cases based on critical points

Theorems

Properties of Absolute Value
Inequality Theorem: Solutions depend on different intervals

Suitable Grade Level

Grades 9-11