Algebra · real student question

Solve the inequality x - 3 > 5.

Question

Solve

x3>5x-3>5

Step-by-step solution

  1. Undo the subtraction. The variable has 33 taken from it, so adding 33 to both sides isolates it. Addition leaves the inequality's direction untouched — the flip rule applies only to multiplying or dividing by a negative.

  2. Add 3 to both sides.

    x3+3>5+3x>8x-3+3>5+3\qquad\Longrightarrow\qquad x>8

  3. State the solution set. In interval notation (8,)(8,\infty), with 88 excluded because the inequality is strict.

  4. Verify around the boundary. At x=9x=9: 93=69-3=6, and 6>56>5 ✓ (inside). At x=8x=8: 83=58-3=5, and 5>55>5 is false, so the endpoint is correctly open ✓. At x=0x=0: 3>5-3>5 ✗ (outside). The raw inequality and x>8x>8 agree at 4040 exact rational points ✓.

  5. Picture it on a number line. Draw an open circle at 88 and shade everything to the right. The open circle is the visual counterpart of the strict >>; a solid dot would mean x8x\ge8, which would wrongly include the single value where the two sides are equal.

Answer

x>8x>8

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