[tex]$a+a r+a r^{2}+\ldots \infty=15$$a^{2}+(a r)^{2}+\left(a r^{2}\right)^{2}+\ldots \infty=150$. Find $a r^{3}+a r^{4}+a r^{6}+\ldots \infty$[/tex]
Options:
[tex](a) $\frac{1}{2}$\\(b) $\frac{2}{5}$[/tex]

Answers

Answer 1

Let

[tex]S_n = \displaystyle \sum_{k=0}^n r^k = 1 + r + r^2 + \cdots + r^n[/tex]

where we assume |r| < 1. Multiplying on both sides by r gives

[tex]r S_n = \displaystyle \sum_{k=0}^n r^{k+1} = r + r^2 + r^3 + \cdots + r^{n+1}[/tex]

and subtracting this from [tex]S_n[/tex] gives

[tex](1 - r) S_n = 1 - r^{n+1} \implies S_n = \dfrac{1 - r^{n+1}}{1 - r}[/tex]

As n → ∞, the exponential term will converge to 0, and the partial sums [tex]S_n[/tex] will converge to

[tex]\displaystyle \lim_{n\to\infty} S_n = \dfrac1{1-r}[/tex]

Now, we're given

[tex]a + ar + ar^2 + \cdots = 15 \implies 1 + r + r^2 + \cdots = \dfrac{15}a[/tex]

[tex]a^2 + a^2r^2 + a^2r^4 + \cdots = 150 \implies 1 + r^2 + r^4 + \cdots = \dfrac{150}{a^2}[/tex]

We must have |r| < 1 since both sums converge, so

[tex]\dfrac{15}a = \dfrac1{1-r}[/tex]

[tex]\dfrac{150}{a^2} = \dfrac1{1-r^2}[/tex]

Solving for r by substitution, we have

[tex]\dfrac{15}a = \dfrac1{1-r} \implies a = 15(1-r)[/tex]

[tex]\dfrac{150}{225(1-r)^2} = \dfrac1{1-r^2}[/tex]

Recalling the difference of squares identity, we have

[tex]\dfrac2{3(1-r)^2} = \dfrac1{(1-r)(1+r)}[/tex]

We've already confirmed r ≠ 1, so we can simplify this to

[tex]\dfrac2{3(1-r)} = \dfrac1{1+r} \implies \dfrac{1-r}{1+r} = \dfrac23 \implies r = \dfrac15[/tex]

It follows that

[tex]\dfrac a{1-r} = \dfrac a{1-\frac15} = 15 \implies a = 12[/tex]

and so the sum we want is

[tex]ar^3 + ar^4 + ar^6 + \cdots = 15 - a - ar - ar^2 = \boxed{\dfrac3{25}}[/tex]

which doesn't appear to be either of the given answer choices. Are you sure there isn't a typo somewhere?


Related Questions

ARGENTTTT!!!!
Which statement describes the difference in the distance
travelled by the two cars when 15 gallons of gasoline is used?
Both cars will have travelled the same distance.

Answers

Answer:

  D.  A travels 90 miles more

Step-by-step explanation:

The graph tells you Car A travels 140 miles on 5 gallons of gas. (There is a point marked there on the graph.)

The table tells you Car B travels 99 miles on 4.5 gallons of gas. When that is multiplied by 5/4.5 = 10/9 to get the equivalent for 5 gallons, we see that Car B could travel 10/9 × 99 = 110 miles on 5 gallons of gas.

__

Already on 5 gallons of gas, Car A has traveled 30 miles farther. The only sensible answer choice is ...

  D.  Car A travelled 90 miles more than Car B [when 15 gallons are used].

can someone help me solve this?

Answers

Answer:

[tex]\dfrac{7\pi}{18}[/tex]

Step by step explanation:

[tex]70^{\circ}=\dfrac{70\pi}{180}~~\text{radians}=\dfrac{7\pi}{18}~~\text{radians}[/tex]

This graph shows a proportional relational between the distance traveled by Tim on a road trip and the number
of hours for which he traveled.
Distance Traveled by Tim
250
200
150
Distance (mi)
100
50
0
10
6 8
Number of Hours
Which statement identifies the correct slope and the correct interpretation of the slope for this situation?
50
A The slope of the line is
1
so the distance traveled by Tim is miles every hour.
50
B The slope of the line is so the distance traveled by Tim is miles every hours.
1
1
The slope of the line is
50
so the distance traveled by Tim is miles every hour.

Answers

Using the proportional relationship, it is found that the correct statement regarding the slope of the relation is:

The slope of the line is of 25, so the distance traveled by Tim is 25 miles every hour.

What is a proportional relationship?

A proportional relationship is a function in which the output variable is given by the input variable multiplied by a constant of proportionality, that is:

y = kx

In which k is the constant of proportionality, which is also called the slope.

Researching the problem on the internet, it is found that in 2 hours, Tim traveled 50 miles, hence:

k = 50/2 = 25.

The slope of the line is of 25, so the distance traveled by Tim is 25 miles every hour.

More can be learned about proportional relationships at https://brainly.com/question/10424180

PLEASE HELP PLEASE HELPP

Answers

Answer:

B

Step-by-step explanation:

Coordinates are (x,y) so just look at the table on how the x-value compares.

Answer:

answer is B

pls give me branlist

Let g: R+R+ be defined by g(x) = x2 +1. Determine the domain, co-domain and range of g. ​

Answers

g(x)=x²+1

Domain:-

For any real x function is not undefined .

Domain belongs to R

Codomain belongs to R+

Range:-

x² always ≥0

Hence

range=[1,oo)

Susan gave 1/6 of a pizza to her brother. She gave 1/3 of what was left to
her mother. Susan ate the rest herself. What fraction of the pizza did Susan
eat?
°1/2
°1/9
°1/18
°5/9

Answers

Answer:1/2

Step-by-step explanation: after giving some to her brother she has 5/6 left to take 1/3 from that you need to make it have a common denominator. to do that multiply it by 2 so you get 2/6. then do 5/6-2/6=3/6. 3/6 simplied is 1/2.

A coordinate plane with 3 points plotted at (10, 18), (14, 24), and (18, 30).
Which statement describes the function through the points?

Answers

Answer:

They are all even

Step-by-step explanation:

Find the product of 0.000879 and 1.028

Answers

Answer:

0.008791747

Step-by-step explanation:  

0.000879  

x       1.028

-------------------

         0167

       01580

   000000

08790000

---------------------

  8791747

0.000879 and 1.028 have NINE decimal places total, so add NINE decimal places from the LEFT to the above answer.

Final answer: 0.008791747

I hope this helps!

X - 8 = 1 what does X equal to?

Answers

Answer:

9

Step-by-step explanation:

To answer this we add 8 to both sides:

x-8+8 = 1+8

x = 9

This is our answer

Given:-

X - 8 = 1

To find :-

The value of x

Solution :-

X - 8 = 1

Transferring 8 to Right side

X = 1 + 8 ( signs change when transferred to opposite side )

X = 9

I need help please I am good at read not math so please help I don't get it ):​

Answers

Answer: 782

Step-by-step explanation

It says it made a w

Answer:

Part A: Andy is incorrect

Part B: 3/20

Step-by-step explanation:

Part A: Since Andy:

Actions dvds = 3/5

Comedy dvds = 1/4

or = Add

3/5 + 1/4

12 + 5 /20 = 17/20

Thus, it doesn't equal to 4/9.

Part B: He needed to make 3/5 = 12/20 and 1/4 = 5/20.  Adding these together would be 17/20, making 3/20 of them NOT action or comedy.  17/20 + 3/20 = 20/20 or the total.

Therefore, 3/20 of them Not action or comedy.

~lenvy~

What is the mode of the data represented in this line plot?

Enter your answer in the box.

Answers

Answer:

3

Step-by-step explanation:

The mode is 3 because it is the most commonly repeating number in the data set.

The mode of the data represented in this line plot is 3

How to determine the mode?

From the line plot, we have the following frequency table

Data   Frequency

1               2

2            3

3            4

4            3

In the above frequency table, the entry 3 has the highest frequency of 4

Hence. the mode of the data is 3

Read more about mode at:

https://brainly.com/question/14532771

#SPJ2

Write a proportion for the statement.
$118 per week is proportional to $472 per 4 weeks. The proportion is _____?

Answers

Writing Proportions

A proportion is a mathematical comparison between two ratios.

A ratio is a comparison between two numbers.

For instance, the ratio of apples to bananas in a fruit basket is 1 apple to 2 bananas:

[tex]\dfrac{1\hspace{3}apple}{2\hspace{3}bananas}[/tex]

This is proportional to the ratio of apples to bananas in another fruit basket, which is 2 apples to 4 bananas:

[tex]\dfrac{2\hspace{3}apples}{4\hspace{3}bananas}[/tex]

To write a proportion from this information, we can compare the ratios by makign them equal to each other:

[tex]\dfrac{1\hspace{3}apple}{2\hspace{3}bananas}=\dfrac{2\hspace{3}apples}{4\hspace{3}bananas}[/tex][tex]\dfrac{1}{2}=\dfrac{2}{4}[/tex]

Solving the Question

We're given:

$118 per week$472 per 4 weeksThese are proportional

$118 per week is one ratio:

[tex]\dfrac{118\hspace{3}dollars}{1\hspace{3}week}[/tex]

$472 per 4 weeks is another ratio:

[tex]\dfrac{472\hspace{3}dollars}{4\hspace{3}weeks}[/tex]

Now, set them equal to each other to create a proportion:

[tex]\dfrac{118\hspace{3}dollars}{1\hspace{3}week}=\dfrac{472\hspace{3}dollars}{4\hspace{3}weeks}\\\\\dfrac{118}{1}=\dfrac{472}{4}[/tex]

Answer:

Therefore, the proportion is [tex]\dfrac{118}{1}=\dfrac{472}{4}[/tex].

What is the volume of the prism?

Answers

Answer:

[tex]the \: volume \: of \: a \: rectangular \: prism \: is \\ l \times w \times h \\ in \: this \: graph \: \\ l = 2 \frac{1}{4} \\ w = 2 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \ \: \: \: \: \: h = 4 \\ 2 \frac{1}{4} \times 2 \times 4 \\ 4 \frac{1}{2} \times 4 = 18 \\ the \: volume \: is \: 18 {in}^{3} [/tex]

I don’t get 2 and 3 I really need help

Answers

Answer:

Step-by-step explanation:

Opposite angles of a cyclic quadrilateral sum to 180 so

m < x = 180-105 = 75 degrees

m < y = 180 - 95 = 85 degrees.

Select the correct answer.
A company designs a new water pitcher. They take a picture of the pitcher for their promotional materials. What is the approximate area filled
by the water in the picture on the flyers?
5 in
4 in
3 in
12 in
8 in
О А.
about 48 in?
B. about 66 in?
Oc about 32 in?
OD. about 80 in?

Answers

Applying the area of trapezium, the approximate area filled by water in the picture would be close to: about 48 in.²

What is the Area of a Trapezium?

Area of trapezium = 1/2(a + b)h.

The following are dimensions of the area of the trapezium filled with water:

Level of water (a) = median of the bigger trapezium = (3 + 8)/2 = 5.5 = 6 in.b = 8 in.Height ≈ 12/2 = 6 in.

Area = 1/2(6 + 8) × 6 = 42 in.²

Therefore, applying the area of trapezium, the approximate area filled by water in the picture would be close to: about 48 in.²

Learn more about area of trapezium on:

https://brainly.com/question/16904048

4 + (x + y) = (4 + x) + y =
what are the properties?​

Answers

Answer:

Distributive

Step-by-step explanation:

What is the slope of a line perpendicular to the line whose equation is
3x – 3y = 63. Fully simplify your answer.

Answers

the answer is - m=1

use the slope intercept form. y=mx+b

In a Right Triangle, if the measurement for the base (B) equals a negative 6 and the hypotenuse equals (C) equals 12, then what is the value of the side (A)?

Answers

Explanation:
Use pythagorean theorem: a^2+b^2=c^2
a^2+(-6)^2=(12)^2
a^2+36=144
a^2=108
a≈12.58

HELP ASAP FIRST GET BRAINIEST

!!!!!!!!!!!!!!!!!!!!!!!!!

Answers

Answer:

C

Step-by-step explanation:

just imagine that they are folding and what they would fold into.

this kind of question is a memory test.

Hope this helps!

Brainliest please!

Please fully rate!

Have a great day!

Oscar enjoys many different sports. Today, Oscar jogged for 6 minutes, rode his bike for 23 minutes, and played tennis for 49 minutes.

How much time did Oscar spend playing sports today?

Answers

Answer: 78

Step-by-step explanation:

just add the time all together then this will be your answer.

Which expression is equivalent?

Answers

Answer:

The Third one.

Step-by-step explanation:

So, Turn the mixed number, 2 1/4, to an improper fraction, 9/4. Then match the answer!

If you need anything else, just message me!

Have a nice day! :)



A solid has volume 7 cubic units. The equation k =
represents the scale factor of k by which
the solid must be dilated to obtain an image with volume V cubic units. Select all points which are
on the graph representing this equation.
a. (0,0)
e. (14,2)
b. (1,1)
f. (49,2)
C. (1,7)
(
g. (56,2)
(71)
h (27,3)

Answers

The volume of the solid is the amount of space in it.

The points on the graph are (0,0) and (1,7)

How to determine the points?

The volume is given as:

V1 = 7

The scale factor is given as:

k

Let the new volume be V.

So, we have:

V = V1 * k^3

Substitute 7 for V1

V = 7k^3

Divide both sides by 7

k^3 = V/7

Take the cube root of both sides

k = (V/7)^1/3

Next, we test the options

a. (0,0)

k = (0/7)^1/3

k = 0 --- this is true

b. (1,1)

k = (1/7)^1/3

k = 0.05 --- this is false

c. (1,7)

k = (7/7)^1/3

k = 1 --- this is true

d (7, 1)

k = (1/7)^1/3

k = 0.05 --- this is false

e. (14,2)

k = (2/7)^1/3

k = 0.10 --- this is false

f. (49,2)

k = (2/7)^1/3

k = 0.10 --- this is false

g. (56,2)

k = (2/7)^1/3

k = 0.10 --- this is false

h (27,3)

k = (3/7)^1/3

k = 0.14 --- this is false

Hence, the points on the graph are (0,0) and (1,7)

Read more about volumes at:

https://brainly.com/question/12232378

For questions 4 – 6, name all of the radii of the circle shown in the figure.
For questions 7 – 10, find the measure of the radius of the circle. 7. 8.

Answers

For questions 4 – 6, name all of the radii of the circle shown in the figure.

For questions 7 – 10, find the measure of the radius of the circle. 7. 8.

Answer:

center(-2,5) r=6

The area of a circle is 9π m². What is the circumference, in meters? Express answer in terms of π

Answers

Answer:

20.25 pi

Step-by-step explanation:

The circumference of a circle is given by

C = 2 * pi *r

9 pi = 2 * pi *r

Divide each side by 2pi

9pi / 2 pi = 2 pi r / 2 pi

4.5 = r

Now we can find area

A = pi r^2

= pi ( 4.5)^2

20.25 pi

can someone solve this ​

Answers

Answer:

check the image for solution

Step-by-step explanation:

Read the sentence.

When my cousin Jason suddenly showed up out of the blue, it was an unexpected surprise because we had no idea that he was coming to the special event that our family had planned ahead of time.

Which revision most effectively shortens the sentence to make it less repetitive and more precise?

Drag the revision into the box.

Answers

The first sentence is correct.

Answer: We were surprised when my cousin jason attended our family reunion.

Step-by-step explanation: I took the k12 quiz and got it right.

how i do this? help pls

Answers

Factor the left side of the equation.

If any individual factor on the left side of the equation is equal to 0, the entire expression will be equal to 0.

Set the first factor equal to 0.

Set the next factor equal to 0 and solve.

Set the next factor equal to 0 and solve.

The final solution is all the values that make

solve for x ~
[tex]81x - 27x = 9[/tex]



thankyou ~​

Answers

Listen ducky: 81x-27x=9

54x=9

X=1

---

6

[tex]\qquad\qquad\huge\underline{{\sf Answer}}[/tex]

Here we go ~

[tex]\qquad \tt \dashrightarrow \:81x - 27x = 9[/tex]

[tex]\qquad \tt \dashrightarrow \:9(9x - 3x )= 9[/tex]

[tex]\qquad \tt \dashrightarrow \:(9x - 3x )= 1[/tex]

[tex]\qquad \tt \dashrightarrow \:6x = 1[/tex]

[tex]\qquad \tt \dashrightarrow \:x = \cfrac{1}{6} [/tex]

A swimming pool is in the shape of a cylinder 7 feet deep and 9 feet in radius. Find the exact volume of the pool.

Answers

Answer:

16

Step-by-step explanation:

Hope this helps

Please help! First answer correct BRAINLIEST

Answers

Answer:

8 in

Step-by-step explanation:

Area=(1/2)*(p1+p2)*d

Other Questions
Sample question.....asajs can someone help me how to do this pls HELP ASAPThe function f(x) = x2 4x + 5 is shown on the graph. On a coordinate plane, a parabola opens down. It goes through (negative 5, 0), has a vertex at (negative 2, 9), and goes through (1, 0). Which statement about the function is true? The domain of the function is all real numbers less than or equal to 2. The domain of the function is all real numbers less than or equal to 9. The range of the function is all real numbers less than or equal to 2. The range of the function is all real numbers less than or equal to 9 According to Article 3 of theConstitution, what branch controls theSupreme Court?A. JudicialB. ExecutiveC. Legislative display unit is capable of displaying test but not 9. A 2.00 L flask is filled with propane gas (CH) at a pressure of 1.00 atm and atemperature of -15.0C. What is the mass of the propane in the flask? HELPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP Do you believe its possible for non-Christians or those who dont hold Scripture as a sacred text to believe in the sanctity of human life? Why or why not? When bonds are issued at their face amount, the journal entry will include a __________ to __________.a. credit; Premium on Bonds Payableb. debit; Discount on Bonds Payablec. credit; Cashd. credit; Bonds Payable If a person is putting in 500 J of work in a 25 second period, how much power are they producing? What conclusion can be drawn from the map? Please help with this its really hard :( Consider three independently assorting gene pairs, A/a, B/b, and C/c, where each demonstrates a typical dominance (A-, B-, C-) and recessiveness (aa, bb, cc) relationship. What is the probability of obtaining an offspring that is triply dominant from parents that are AaBbcc and AaBbCc Which sentence is most likely meant to create suspense for the reader?Stealing the Dayby Samantha G. (excerpt)tachieved the unofficial "smart kid" designation in elementary school and it was not until years later that I met someone who threatened to depose me from my reign.His name was George, after our nation's first president, and he had been the smartest kid in school during his early academic career as wellt but George grew up on theother side of town, so we had really never crossed paths. We were introduced in our biology class, seated at opposite ends of the first row of desks. When our teacherbegan asking basic questions to test our science knowledge, George and I had not even noticed each other's existence.But when Mr. Hartley inquired about the aardvark's natural habitat, both of us shot a hand into the air."Africal" exploded the dual shout, followed by snickering from the rest of the class. I peeked in the direction of the other voice to see George gazing directly ahead, asthough he was oblivious to anyone else. Surely, he perceived the awkwardness of this circumstance, and had the abrupt comprehension that there was another "smart kidin the school But no acknowledgment crossed his face, and I stared back at my own desk as class continued.When the bell rang and students began jostling out the door, I hung back, thinking that I should at least introduce myself to George. He had waited for everyone else topush out of the classroom as well, and I extended my hand toward him with a smile."just wanted to let you know that I plan to outdo you in every class we have together this semester, and every semester until graduation," he said.Without glancing in my direction, George dashed out the door and down the hall toward his locker, I was left in shock at his words, at the audacity of his confidence andconceit. After standing immobile for a few moments, I ducked out the side door of the classroom into the late summer sunshine to comprehend what had just transpiredUltimately, I came to the apparent explanation to his immature attack George perceived me as a threat. Find the volume please help I don't understand. A custodian can clean 2 classrooms in 15 minutes. At this rate, how many classrooms can a custodian clean in 76 minutes? Solve for h. h - 45 = -35A.h = -10B.h = 10C.h = -80D.h = 80PLS HELP HURRY Calculate the cell potential for the galvanic cell in which the given reaction occurs at 25 C, given that [Cd2+]=0.00190 M and [Au3+]=0.788 M . Standard reduction potentials can be found in this table. 3Cd(s)+2Au3+(aq)3Cd2+(aq)+2Au(s) Please help me with this please and thank you Nico has conducted an observational study to learn about how different personal experiences affect car purchases. nico surveyed 300 new car buyers at the auto mall and found that 75% of the buyers were shopping for the same model of a car they have owned before. what conclusion can nico make from his study?