Algebra (Inequalities)

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Compound inequality: solve both halves, intersect

Question: Solve 92x+1<52x23x+1\dfrac{9}{2}x + 1 < \dfrac{5}{2}x - 2 \le 3x + 1 and show the answer on a number line.

Step 1. A chain is two inequalities sharing the middle expression. Split it:

(i)    92x+1<52x2(ii)    52x23x+1\text{(i)}\;\; \dfrac{9}{2}x + 1 < \dfrac{5}{2}x - 2 \qquad \text{(ii)}\;\; \dfrac{5}{2}x - 2 \le 3x + 1

Step 2. Solve (i):

92x52x<3    2x<3    x<32\dfrac{9}{2}x - \dfrac{5}{2}x < -3 \;\Rightarrow\; 2x < -3 \;\Rightarrow\; x < -\dfrac{3}{2}

Step 3. Solve (ii):

213x52x    312x    x6-2 - 1 \le 3x - \dfrac{5}{2}x \;\Rightarrow\; -3 \le \dfrac{1}{2}x \;\Rightarrow\; x \ge -6

Step 4. Both must hold — take the overlap:

6x<32-6 \le x < -\dfrac{3}{2}

Number line: filled circle at 6-6 (from \le), open circle at 32-\frac{3}{2} (from <<), shaded between. If asked for integer values: 6,5,4,3,2-6, -5, -4, -3, -2.

⚠ Watch out: Never chain-solve across all three parts at once when xx lives in every piece — split, solve, intersect. The two circles usually differ (one filled, one open); copying the same style onto both is the giveaway of a rushed answer.

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