Question

Find the sum of the first 8 terms of the following sequence. Round to the nearest hundredth if necessary

Answer 1

The sum of the first 8 terms is 2.51 to the nearest hundredth

Step-by-step explanation:

In the geometric sequence there is a constant ratio between each two consecutive terms

The formula of the sum of n terms of a geometric sequence is:

$S_{n}=\frac{a(1-r^{n})}{1-r}$ , where

• a is the first term
• r is the constant ratio between the consecutive terms

∵ The sequence is 6 , -5 , 25/6 , .............

∵ -5 ÷ 6 = $\frac{-5}{6}$

∵ $\frac{25}{6}$ ÷ -5 = $\frac{-5}{6}$

- There is a constant ratio between the consecutive terms

∴ The sequence is a geometric sequence

∵ The first term is 6

∴ a = 6

∵ The constant ratio is $\frac{-5}{6}$

∴ r =  $\frac{-5}{6}$

∵ We need to find the sum of 8 terms

∴ n = 8

- Substitute the values of a, r and n in the rule above

∴ $S_{8}=\frac{6[1-(\frac{-5}{6})^{8}]}{1-(\frac{-5}{6})}$

∴ $S_{8}=2.511595508$

- Round it to the nearest hundredth

∴ $S_{8}=2.51$

The sum of the first 8 terms is 2.51 to the nearest hundredth

Learn more:

You can learn more about the sequences in brainly.com/question/7221312

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