find the function represented by the following series and find the interval of convergence of the series. \n…

find the function represented by the following series and find the interval of convergence of the series. \n sum_{k = 0}^{infty}\frac{(x - 5)^{2k}}{4^{k}} \nthe function represented by the series sum_{k = 0}^{infty}\frac{(x - 5)^{2k}}{4^{k}} is ( f(x)=square ).

find the function represented by the following series and find the interval of convergence of the series. \n sum_{k = 0}^{infty}\frac{(x - 5)^{2k}}{4^{k}} \nthe function represented by the series sum_{k = 0}^{infty}\frac{(x - 5)^{2k}}{4^{k}} is ( f(x)=square ).

Answer

Explanation:

Step1: Recognize geometric - series form

The given series $\sum_{k = 0}^{\infty}\frac{(x - 5)^{2k}}{4^{k}}=\sum_{k = 0}^{\infty}(\frac{(x - 5)^{2}}{4})^{k}$. A geometric series has the form $\sum_{k=0}^{\infty}ar^{k}$, where $a = 1$ and $r=\frac{(x - 5)^{2}}{4}$.

Step2: Use geometric - series formula

For a geometric series $\sum_{k = 0}^{\infty}ar^{k}$, when $|r|\lt1$, the sum is given by $S=\frac{a}{1 - r}$. Here, since $a = 1$ and $r=\frac{(x - 5)^{2}}{4}$, the function $f(x)=\frac{1}{1-\frac{(x - 5)^{2}}{4}}=\frac{4}{4-(x - 5)^{2}}=\frac{4}{4-(x^{2}-10x + 25)}=\frac{4}{-x^{2}+10x - 21}$.

Step3: Find interval of convergence

For a geometric series $\sum_{k = 0}^{\infty}r^{k}$ to converge, $|r|\lt1$. So, $|\frac{(x - 5)^{2}}{4}|\lt1$. This implies $(x - 5)^{2}\lt4$. Taking the square - root of both sides, we get $|x - 5|\lt2$. Solving the inequality:

  • $x-5\lt2$ gives $x\lt7$.
  • $-(x - 5)\lt2$ (or $x-5\gt - 2$) gives $x\gt3$.

Answer:

The function $f(x)=\frac{4}{4-(x - 5)^{2}}$ and the interval of convergence is $(3,7)$.