If $f(x)=x^2+2$, which of the following could be a value of $f(x)$ ?

Note that the problem is asking which of the answers could be equal to $f(x)$-in other words, the problem is asking which of these values could be spit out of the $f(x)$ machine. Think about what is going in: No matter what you put in as a value for $x$, the value of $x^2$ has to be positive or zero. So, the lowest possible value of $x^2+2$ is 2 , which is $(\mathrm{D})$ Note that you could also approach this question by Plugging In the Answers. If you plugged in 1 for $f(x)$, for instance, you would get $1=x^2+2$, which becomes $x^2=-1$, which is impossible.