Set 15: Quadratic Equations (Intermediate)

Choice A is correct. Choice A is the correct answer. 1. $x^2$ is always $\geq 0$ for any real number. 2. Adding 1 means $x^2 + 1 \geq 1$. 3. Since $1> 0$, the expression is always positive. 4. Therefore, the solution is all real numbers. Choice B is incorrect. Choice C is incorrect. Choice D is incorrect.