IDNLearn.com is the perfect place to get answers, share knowledge, and learn new things. Get accurate answers to your questions from our community of experts who are always ready to provide timely and relevant solutions.

Sum the terms of the following series:

[tex]\[ 1+\frac{2}{2}+\frac{3}{2^2}+\frac{4}{2^3}+\cdots \][/tex]


Sagot :

Certainly! Let's analyze the series provided: [tex]\( 1 + \frac{2}{2} + \frac{3}{2^2} + \frac{4}{2^3} + \cdots \)[/tex].

We are asked to sum the first few terms of this series. Let's denote each term of the series as [tex]\( a_n \)[/tex], where [tex]\( n \)[/tex] represents the position of the term in the series. In general, the [tex]\( n \)[/tex]-th term [tex]\( a_n \)[/tex] of this series is given by:

[tex]\[ a_n = \frac{n}{2^{n-1}} \][/tex]

Now, we will identify the number of terms to sum. We will sum the first 10 terms of the series. Here are the first 10 terms calculated individually:

1. For [tex]\( n = 1 \)[/tex]:
[tex]\[ a_1 = \frac{1}{2^{1-1}} = \frac{1}{1} = 1 \][/tex]

2. For [tex]\( n = 2 \)[/tex]:
[tex]\[ a_2 = \frac{2}{2^{2-1}} = \frac{2}{2} = 1 \][/tex]

3. For [tex]\( n = 3 \)[/tex]:
[tex]\[ a_3 = \frac{3}{2^{3-1}} = \frac{3}{4} = 0.75 \][/tex]

4. For [tex]\( n = 4 \)[/tex]:
[tex]\[ a_4 = \frac{4}{2^{4-1}} = \frac{4}{8} = 0.5 \][/tex]

5. For [tex]\( n = 5 \)[/tex]:
[tex]\[ a_5 = \frac{5}{2^{5-1}} = \frac{5}{16} = 0.3125 \][/tex]

6. For [tex]\( n = 6 \)[/tex]:
[tex]\[ a_6 = \frac{6}{2^{6-1}} = \frac{6}{32} = 0.1875 \][/tex]

7. For [tex]\( n = 7 \)[/tex]:
[tex]\[ a_7 = \frac{7}{2^{7-1}} = \frac{7}{64} = 0.109375 \][/tex]

8. For [tex]\( n = 8 \)[/tex]:
[tex]\[ a_8 = \frac{8}{2^{8-1}} = \frac{8}{128} = 0.0625 \][/tex]

9. For [tex]\( n = 9 \)[/tex]:
[tex]\[ a_9 = \frac{9}{2^{9-1}} = \frac{9}{256} = 0.03515625 \][/tex]

10. For [tex]\( n = 10 \)[/tex]:
[tex]\[ a_{10} = \frac{10}{2^{10-1}} = \frac{10}{512} = 0.01953125 \][/tex]

To obtain the sum of these terms, we add them together:

[tex]\[ 1 + 1 + 0.75 + 0.5 + 0.3125 + 0.1875 + 0.109375 + 0.0625 + 0.03515625 + 0.01953125 \][/tex]

Adding these values, we get:

[tex]\[ 1 + 1 = 2 \\ 2 + 0.75 = 2.75 \\ 2.75 + 0.5 = 3.25 \\ 3.25 + 0.3125 = 3.5625 \\ 3.5625 + 0.1875 = 3.75 \\ 3.75 + 0.109375 = 3.859375 \\ 3.859375 + 0.0625 = 3.921875 \\ 3.921875 + 0.03515625 = 3.95703125 \\ 3.95703125 + 0.01953125 = 3.9765625 \][/tex]

Therefore, the sum of the first 10 terms of the series [tex]\( 1 + \frac{2}{2} + \frac{3}{2^2} + \frac{4}{2^3} + \cdots \)[/tex] is:

[tex]\[ \boxed{3.9765625} \][/tex]