OG详解-OG1 数学1 Q4

Choice A is correct. It’s given that g(x) =x²+9. Substituting 25 for g(x) in this equation yields 25 =x²+9. Subtracting 9 from both sides of this equation yields 16= x². Taking the square root of each side of this equation yields x = ±4. It follows that g(x)=25 when the value of x is 4 or -4. Only 4 is listed among the choices.
Choice B is incorrect and may result from conceptual or calculation errors. 
Choice C is incorrect and may result from conceptual or calculation errors. 
Choice D is incorrect and may result from conceptual or calculation errors.