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Partial sums approximate the function by truncating the infinite series after a finite number of terms to create a polynomial. As more terms are added, the polynomial matches the target function's graph more closely over a wider interval around the origin.

Conditions: The approximation is evaluated near the center of expansion ($x=0$).; A finite number of terms is selected from the infinite series.

Partial sums approximate the function by truncating the infinite series after a finite number of terms to create a polynomial. As more terms are added, the polynomial matches the target function's graph more closely over a wider interval around the origin.

Conditions: The approximation is evaluated near the center of expansion ($x=0$).; A finite number of terms is selected from the infinite series.

To expand the summation, substitute successive integer values for the index $k$ into the general term. For $k=0$, the term simplifies to $1$.

Conditions: The summation index $k$ starts at $0$ and increases by $1$ for each term.; The general term is $\frac{(-1)^k x^{2k}}{(2k)!}$.

To expand the summation, substitute successive integer values for the index $k$ into the general term. For $k=0$, the term simplifies to $1$.

Conditions: The summation index $k$ starts at $0$ and increases by $1$ for each term.; The general term is $\frac{(-1)^k x^{2k}}{(2k)!}$.

To determine if an infinite series converges or diverges when given an explicit formula for its $n$-th partial sum $S_n$, evaluate the limit $\lim_{n \to \infty} S_n$. If this limit exists and is a finite value, the series converges to that value; if the limit is infinite or does not exist, the series diverges.

Conditions: You are given an explicit algebraic formula for the $n$-th partial sum, $S_n$.; The limit is taken as $n \to \infty$.

To determine if an infinite series converges or diverges when given an explicit formula for its $n$-th partial sum $S_n$, evaluate the limit $\lim_{n \to \infty} S_n$. If this limit exists and is a finite value, the series converges to that value; if the limit is infinite or does not exist, the series diverges.

Conditions: You are given an explicit algebraic formula for the $n$-th partial sum, $S_n$.; The limit is taken as $n \to \infty$.