4Compound inequality
Solve −3 < 2x + 1 ≤ 9.
The solution is −2 < x ≤ 4. Subtracting 1 from all three parts of −3 < 2x+1 ≤ 9 gives −4 < 2x ≤ 8, then dividing by 2 gives −2 < x ≤ 4. Checking x = 4: 2(4)+1 = 9 ✓.
Solve −3 < 2x + 1 ≤ 9.
The solution is −2 < x ≤ 4. Subtracting 1 from all three parts of −3 < 2x+1 ≤ 9 gives −4 < 2x ≤ 8, then dividing by 2 gives −2 < x ≤ 4. Checking x = 4: 2(4)+1 = 9 ✓.