4
advanced-math

Solve: (x1)2=5(x - 1)^2 = 5

A

x=1±5x = 1 \pm \sqrt{5}

B

x=1±5x = -1 \pm \sqrt{5}

C

x=±6x = \pm \sqrt{6}

D

x=5±1x = 5 \pm 1

Correct Answer: A

Choice A is the correct answer.

  1. Take the square root of both sides: x1=±5x - 1 = \pm \sqrt{5}.
  2. Add 1 to both sides to isolate x: x=1±5x = 1 \pm \sqrt{5}.

This represents two irrational solutions: 1+51 + \sqrt{5} and 151 - \sqrt{5}.

Choice B is incorrect because of a sign error (subtracted 1 instead of adding). Choice C is incorrect because it adds 1 inside the radical, which is invalid. Choice D is incorrect because it swaps the order of operations.