Algebra · real student question

Solve the inequality x/2 > x - 1.

Question

Solve

x2>x1\frac{x}{2}>x-1

Step-by-step solution

  1. Clear the fraction by multiplying by 2. The multiplier 22 is positive, so the inequality direction is unchanged — this is safe in a way that multiplying by a variable would not be:

    x>2(x1)=2x2x>2(x-1)=2x-2

    Note the 22 must reach both terms of x1x-1.

  2. Collect the variable terms. Subtract 2x2x from both sides:

    x2x>2x>2x-2x>-2\qquad\Longrightarrow\qquad-x>-2

    The coefficient is now negative, which sets up the one step that requires care.

  3. Multiply by 1-1 and reverse the inequality. Negating both sides of an inequality flips its direction:

    x<2x<2

    Skipping the flip would give the exactly wrong answer x>2x>2, so this is the crux of the problem. The alternative that avoids it entirely: from x>2x2x>2x-2, add 22 and subtract xx to get 2>x2>x directly, then read it backwards as x<2x<2 ✓ — same answer, no negative coefficient.

  4. State the solution set. In interval notation (,2)(-\infty,2), with 22 excluded because the relation is strict.

  5. Verify around the boundary. At x=0x=0: left 00, right 1-1, and 0>10>-1 ✓ (inside). At x=4x=4: left 22, right 33, and 2>32>3 ✗ (outside). At x=2x=2: left 11, right 11 — equal, so the strict inequality fails and the endpoint is correctly open ✓. The raw inequality and x<2x<2 agree at 8080 exact rational points ✓.

Answer

x<2x<2

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