Math Problem Statement

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

Solution

To solve this inequality, we can examine the given expression step-by-step to confirm if the implication x+2<0.34x+8<1.2|x + 2| < 0.3 \Rightarrow |4x + 8| < 1.2 holds.

Step 1: Analyze the inequality x+2<0.3|x + 2| < 0.3

This inequality implies: 0.3<x+2<0.3-0.3 < x + 2 < 0.3 Subtracting 2 from all parts: 2.3<x<1.7-2.3 < x < -1.7

Thus, the solution for x+2<0.3|x + 2| < 0.3 is: x(2.3,1.7)x \in (-2.3, -1.7)

Step 2: Test the implication 4x+8<1.2|4x + 8| < 1.2

We want to see if x(2.3,1.7)x \in (-2.3, -1.7) guarantees that 4x+8<1.2|4x + 8| < 1.2.

Rewrite 4x+8|4x + 8| using the fact that 4x+8=4(x+2)4x + 8 = 4(x + 2): 4x+8=4(x+2)=4x+2|4x + 8| = |4(x + 2)| = 4 |x + 2|

Since x+2<0.3|x + 2| < 0.3, multiplying by 4 gives: 4x+8<40.3=1.2|4x + 8| < 4 \cdot 0.3 = 1.2

Conclusion

Since 4x+8<1.2|4x + 8| < 1.2 directly follows from x+2<0.3|x + 2| < 0.3, the implication x+2<0.34x+8<1.2|x + 2| < 0.3 \Rightarrow |4x + 8| < 1.2 is true.

Would you like further clarification or have any questions?


Here are some related questions you might find interesting:

  1. What happens if we change the range in the initial inequality, say to x+2<0.5|x+2| < 0.5?
  2. How would the result change if we had x+20.3|x + 2| \leq 0.3 instead?
  3. Can this reasoning apply to any expression where a variable term is scaled?
  4. What if x+2>0.3|x + 2| > 0.3? Would the implication still hold?
  5. How would the problem change if we had 4x+81.2|4x + 8| \leq 1.2?

Tip: Inequalities often maintain their direction when multiplying by positive constants, but not when dealing with negatives—always verify signs when solving.

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Math Problem Analysis

Mathematical Concepts

Algebra
Absolute Value Inequalities
Implication in Inequalities

Formulas

|ax + b| < c implies -c < ax + b < c
Scaling absolute value inequalities

Theorems

Properties of absolute value inequalities
Implication in inequalities

Suitable Grade Level

Grades 10-12