My calculus teacher gives us online quizzes about the material we are supposed to learn the next day. This is only the first week. Here is the question:
Hint: Factor the numerator as much as possible. $\displaystyle x^4 - 16 = \underbrace{{\color{red}(x^2 - 4)}(x^2 + 4)}_{\text{By Difference of Squares}} = \hdots$
Factor the red by the difference of squares and see what cancels Then try to evaluate