Question Detail
Question
The nth term of the Maclaurin series expansion of $\cos 3x$ is
Correct Answer
Option D is the correct answer.
Detailed Explanation
The Maclaurin series for $\cos u$ is given by $\sum_{n=0}^{\infty} \frac{(-1)^n u^{2n}}{(2n)!}$.In this case, $u = 3x$. Substituting $u = 3x$ into the formula, we get the nth term as:$\frac{(-1)^n (3x)^{2n}}{(2n)!}$.Thus, option D is the correct answer.
Hint
Recall the Maclaurin series for $\cos u$ and substitute $u=3x$.