Math Problem Statement

show that the indicated implication is true.

  1. |x-3|<0.5 Rightarrow |5x - 15| < 2.5

|x+2|<0.3 Rightarrow |4x + 8| < 1.2

Solution

To show that each implication is true, let's analyze them one at a time.

Problem 1: x3<0.55x15<2.5|x - 3| < 0.5 \Rightarrow |5x - 15| < 2.5

  1. Start with the assumption: We assume x3<0.5|x - 3| < 0.5 and aim to show that 5x15<2.5|5x - 15| < 2.5.
  2. Rewrite 5x15|5x - 15|: Notice that: 5x15=5(x3)|5x - 15| = |5(x - 3)|
  3. Apply the property of absolute values: We can factor out the 5: 5(x3)=5x3|5(x - 3)| = 5 |x - 3|
  4. Substitute from the assumption: Since x3<0.5|x - 3| < 0.5, we get 5x3<50.5=2.55 |x - 3| < 5 \cdot 0.5 = 2.5
  5. Conclusion: This implies 5x15<2.5|5x - 15| < 2.5, as required.

Thus, the first implication is true.


Problem 2: x+2<0.34x+8<1.2|x + 2| < 0.3 \Rightarrow |4x + 8| < 1.2

  1. Start with the assumption: We assume x+2<0.3|x + 2| < 0.3 and aim to show that 4x+8<1.2|4x + 8| < 1.2.
  2. Rewrite 4x+8|4x + 8|: Notice that: 4x+8=4(x+2)|4x + 8| = |4(x + 2)|
  3. Apply the property of absolute values: We can factor out the 4: 4(x+2)=4x+2|4(x + 2)| = 4 |x + 2|
  4. Substitute from the assumption: Since x+2<0.3|x + 2| < 0.3, we get 4x+2<40.3=1.24 |x + 2| < 4 \cdot 0.3 = 1.2
  5. Conclusion: This implies 4x+8<1.2|4x + 8| < 1.2, as required.

Thus, the second implication is also true.


Both implications are valid.


Do you need further details or have any questions?

Related Questions

  1. How do absolute value inequalities behave under scalar multiplication?
  2. What are some other common properties of absolute values used in proofs?
  3. Can these inequalities be solved by considering the ranges of xx explicitly?
  4. How do absolute value inequalities relate to distance on the real number line?
  5. Could this problem be generalized for other linear expressions?

Tip: In inequalities involving absolute values, always consider factoring constants out to simplify the expressions.

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Math Problem Analysis

Mathematical Concepts

Algebra
Absolute Value Inequalities

Formulas

|a(x - c)| = |a||x - c|

Theorems

Properties of Absolute Values
Scalar Multiplication of Absolute Values

Suitable Grade Level

Grades 9-11