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If x satisfies the inequality \(\frac{x - 3}{x - 5} \gt 3\) then \(x\) lies in the interval

  • A.(3,8)
  • B.(0,5)
  • C.(5,6)
  • D.\((-\infty, 3)\)
  • E.(5,8)

Answer: C

\(x\) lies in \((5, 6)\).

Do not multiply across by \(x - 5\), whose sign is unknown. Bring everything to one side instead:

\[ \begin{aligned} \frac{x - 3}{x - 5} - 3 &\gt 0 \\ \frac{x - 3 - 3x + 15}{x - 5} &\gt 0 \\ \frac{2(6 - x)}{x - 5} &\gt 0 \end{aligned} \]

The fraction is positive when the numerator and denominator have the same sign: both positive needs \(x \lt 6\) and \(x \gt 5\); both negative needs \(x \gt 6\) and \(x \lt 5\), impossible. So \(5 \lt x \lt 6\).

Check \(x = 5.5\): \(2.5/0.5 = 5 \gt 3\). Options (3,8) and (5,8) include points such as 7, where the fraction is \(4/2 = 2\), not greater than 3.

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