A
B
C
D
Explanation
Correct answer: D.
Choice D is correct. If , then taking the square root of each side of the equation gives or . Solving these equations for gives or . Of these, is the only solution given as a choice.
Desmos solution:
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect and may result from solving the equation and making a sign error.
Choice B
Choice B is incorrect and may result from solving the equation .
Choice C
Choice C is incorrect and may result from finding a possible value of .