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2 years ago

Find the sum of the first five terms using the geometric series formula for the sequence 1/2, -1,2,-4…

Mathematics

1 answer:

sammy [17]2 years ago

7 0

The sum of the first five terms is 11/2

<h3>How to determine the sum?</h3>

The series is given as:

1/2, -1,2,-4…

Calculate the common ratio of the series using

r = -4/2

Evaluate

r = -2

The sum is then calculated as:

$S_n = a\frac{1 - r^n}{1 - r}$

This gives

$S_n = \frac{1}{2} * \frac{(1 - (-2)^5}{1 + 2}$

Evaluate

$S_n = \frac{1}{2} * \frac{33)}{3}$

Evaluate

$S_n =\frac{11}{2}$

Hence, the sum of the first five terms is 11/2

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I have a hard time understanding this question

Alex73 [517]

Answer:

22m+42 is the answer

Step-by-step explanation:

All you have to do is simplify and add the common factors.

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3 years ago

Each game costs $1.25 and each ride costs $2.75. A boy spent $20.25 all together at the carnival and the number of rides he went

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Answer:

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3 years ago

Find the Y-coordinate of point P that lies 1/3 along segment RS, where R (-7, -2) and S (2, 4).

QveST [7]

Solution:

Given that the point P lies 1/3 along the segment RS as shown below:

To find the y coordinate of the point P, since the point P lies on 1/3 along the segment RS, we have

$\begin{gathered} RP:PS \\ \Rightarrow\frac{1}{3}:\frac{2}{3} \\ thus,\text{ we have} \\ 1:2 \end{gathered}$

Using the section formula expressed as

$[\frac{mx_2+nx_1}{m+n},\frac{my_2+ny_1}{m+n}]$

In this case,

$\begin{gathered} m=1 \\ n=2 \end{gathered}$

where

$\begin{gathered} x_1=-7 \\ y_1=-2 \\ x_2=2 \\ y_2=4 \end{gathered}$

Thus, by substitution, we have

$\begin{gathered} [\frac{1(2)+2(-7)}{1+2},\frac{1(4)+2(-2)}{1+2}] \\ \Rightarrow[\frac{2-14}{3},\frac{4-4}{3}] \\ =[-4,\text{ 0\rbrack} \end{gathered}$

Hence, the y-coordinate of the point P is

$0$

8 0

1 year ago

Please help

Ann [662]

Answer:

1/60 probabiliity

Step-by-step explanation:

You have two independent events that you want to put together.

Let Pr. mean "probability"

Pr(5 from 10 cards and 2 on a dice ) = Pr(5 from 10 cards) * Pr( 2 on a dice)

Pr(5 from 10 cards and 2 on a dice ) =(1/10) * (1/6)

= 1/60

Pr(5 from 10 cards and 2 on a dice ) =0.0167

or 1.67% probability

5 0

3 years ago

What is the sum of the arithmetic sequence 151, 137, 123,..if there are 26 terms?

ElenaW [278]

First term: a1 = 151
common difference: d = -14 (we decrease by 14 each time, eg, 151-14 = 137)

nth term of this arithmetic sequence is...
an = a1+d(n-1)
an = 151+(-14)(n-1)
an = 151-14n+14
an = -14n+165

This will be used in the formula below

Sn = n*(a1+an)/2
<span>Sn = n*(151+(-14n+165))/2
</span><span>S26 = 26*(151+(-14*26+165))/2 ... replace every n with 26
</span>S26 = -624

The final answer here is choice C) -624
<span>
</span>

5 0

3 years ago