Sophie, Adola, and Gilly are debating potential values in the solution set of the compound inequality −2≤2x−2<8

. Sophie says that −2
is a solution. Adola says that 5 is a solution. Gilly says that 2 is a solution. Which person is correct? Enter 1 for Sophie, 2 for Adola, or 3 for Gilly.

1 answer

To determine who is correct in their assessment of the solutions for the compound inequality \(-2 \leq 2x - 2 < 8\), we need to solve the inequality step by step.

Step 1: Break down the compound inequality

The compound inequality consists of two parts:

  1. \(-2 \leq 2x - 2\)
  2. \(2x - 2 < 8\)

Step 2: Solve the first part

  1. \(-2 \leq 2x - 2\)

    To isolate \(x\), we'll first add 2 to both sides: \[ -2 + 2 \leq 2x - 2 + 2 \implies 0 \leq 2x \] Now divide both sides by 2: \[ 0 \leq x \implies x \geq 0 \]

Step 3: Solve the second part

  1. \(2x - 2 < 8\)

    To isolate \(x\), we first add 2 to both sides: \[ 2x - 2 + 2 < 8 + 2 \implies 2x < 10 \] Now divide both sides by 2: \[ x < 5 \]

Step 4: Combine the results

The solution set for the compound inequality \(-2 \leq 2x - 2 < 8\) is: \[ 0 \leq x < 5 \]

This means that any \(x\) that falls within the interval \([0, 5)\) is a solution to the original inequality.

Step 5: Check each person's claim

  • Sophie claims \(x = -2\): This is not a solution because \(-2 < 0\).
  • Adola claims \(x = 5\): This is not a solution because \(5\) is not less than \(5\).
  • Gilly claims \(x = 2\): This is a solution because \(2\) is within the interval \([0, 5)\).

Conclusion

Only Gilly is correct. Therefore, the answer is:

3