10
algebra

Solve: 1x>2\frac{1}{x} > 2 (Non-linear preview)

A

0<x<0.50 < x < 0.5

B

x>0.5x > 0.5

C

x<0.5x < 0.5

D

x>2x > 2

Correct Answer: A

Choice A is the correct answer. Be careful multiplying by xx (sign change if negative).

  1. Case 1 (x>0x > 0): Multiply by xx: 1>2x0.5>x1 > 2x \rightarrow 0.5 > x. Combined with x>0x>0: 0<x<0.50 < x < 0.5.
  2. Case 2 (x<0x < 0): Multiply by xx (reverse sign): 1<2x0.5<x1 < 2x \rightarrow 0.5 < x. But xx must be negative, so no solution here (0.5<x<00.5 < x < 0 is impossible).
  3. Result: 0<x<0.50 < x < 0.5

?�� Strategic Tip: For rational inequalities, consider the sign of the denominator. Or test points: x=0.110>2x=0.1 \rightarrow 10 > 2 (True). x=11>2x=1 \rightarrow 1 > 2 (False).

Choice B is incorrect.Choice C is incorrect because it includes negative numbers. Choice D is incorrect.