Sum to n terms of each of following series. (a) 1 - 7a + 13a ^ 2 - 19a ^ 3+...​

Answers

Answer 1

Notice that the difference in the absolute values of consecutive coefficients is constant:

|-7| - 1 = 6

13 - |-7| = 6

|-19| - 13 = 6

and so on. This means the coefficients in the given series

[tex]\displaystyle \sum_{i=1}^\infty c_i a^{i-1} = \sum_{i=1}^\infty |c_i| (-a)^{i-1} = 1 - 7a + 13a^2 - 19a^3 + \cdots[/tex]

occur in arithmetic progression; in particular, we have first value [tex]c_1 = 1[/tex] and for [tex]n>1[/tex], [tex]|c_i|=|c_{i-1}|+6[/tex]. Solving this recurrence, we end up with

[tex]|c_i| = |c_1| + 6(i-1) \implies |c_i| = 6i - 5[/tex]

So, the sum to [tex]n[/tex] terms of this series is

[tex]\displaystyle \sum_{i=1}^n (6i-5) (-a)^{i-1} = 6 \underbrace{\sum_{i=1}^n i (-a)^{i-1}}_{S'} - 5 \underbrace{\sum_{i=1}^n (-a)^{i-1}}_S[/tex]

The second sum [tex]S[/tex] is a standard geometric series, which is easy to compute:

[tex]S = 1 - a + a^2 - a^3 + \cdots + (-a)^{n-1}[/tex]

Multiply both sides by [tex]-a[/tex] :

[tex]-aS = -a + a^2 - a^3 + a^4 - \cdots + (-a)^n[/tex]

Subtract this from [tex]S[/tex] to eliminate the intermediate terms to end up with

[tex]S - (-aS) = 1 - (-a)^n \implies (1-(-a)) S = 1 - (-a)^n \implies S = \dfrac{1 - (-a)^n}{1 + a}[/tex]

The first sum [tex]S'[/tex] can be handled with simple algebraic manipulation.

[tex]S' = \displaystyle \sum_{i=1}^n i (-a)^{i-1}[/tex]

[tex]\displaystyle S' = \sum_{i=0}^{n-1} (i+1) (-a)^i[/tex]

[tex]\displaystyle S' = \sum_{i=0}^{n-1} i (-a)^i + \sum_{i=0}^{n-1} (-a)^i[/tex]

[tex]\displaystyle S' = \sum_{i=1}^{n-1} i (-a)^i + \sum_{i=1}^n (-a)^{i-1}[/tex]

[tex]\displaystyle S' = \sum_{i=1}^n i (-a)^i - n (-a)^n + S[/tex]

[tex]\displaystyle S' = -a \sum_{i=1}^n i (-a)^{i-1} - n (-a)^n + S[/tex]

[tex]\displaystyle S' = -a S' - n (-a)^n + \dfrac{1 - (-a)^n}{1 + a}[/tex]

[tex]\displaystyle (1 + a) S' = \dfrac{1 - (-a)^n - n (1 + a) (-a)^n}{1 + a}[/tex]

[tex]\displaystyle S' = \dfrac{1 - (n+1)(-a)^n + n (-a)^{n+1}}{(1+a)^2}[/tex]

Putting everything together, we have

[tex]\displaystyle \sum_{i=1}^n (6i-5) (-a)^{i-1} = 6 S' - 5 S[/tex]

[tex]\displaystyle \sum_{i=1}^n (6i-5) (-a)^{i-1} = 6 \dfrac{1 - (n+1)(-a)^n + n (-a)^{n+1}}{(1+a)^2} - 5 \dfrac{1 - (-a)^n}{1 + a}[/tex]

[tex]\displaystyle \sum_{i=1}^n (6i-5) (-a)^{i-1} =\boxed{\dfrac{1 - 5a - (6n+1) (-a)^n + (6n-5) (-a)^{n+1}}{(1+a)^2}}[/tex]


Related Questions

Which set of side lengths forms a right triangle?
O2, 3, 13
O4, 6, 10
O 9, 12, 18
O 15, 36, 39

Answers

Step-by-step explanation:

hope you can understand

Please solve these questions with an explanation

Answers

Answer:

Step-by-step explanation:

Instructions: Complete the following proof by dragging and dropping the
correct reason in the spaces below.
Statement
Complete the Proof
8x5= 2x + 1
6x5=1
6x = 6
x = 1
Reason
1

Someone help proofs aren’t my thing

Answers

The solution to the given linear equation is x=1

Solution to linear equation

Linear equations are equations that has a leading degree of 1.

Given the linear equation as shown below;

8x - 5= 2x + 1

Subtract 2x from both sides

8x - 2x - 5 = 2x + 1-2x

6x - 5  = 1

Add 5 to both sides

6x - 5 + 5 = 5 + 1

6x  = 6

Divide both sides by 6

6x/6 = 6/6

x = 1

Hence the solution to the given linear equation is x=1

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Use the interactive to make a line that passes through the points 3'2 and -1'-1 slope

Answers

The required equation of the line passing the coordinates will be y = 3/4x - 1/4

Equation of a line

The standard equation of a line is expressed as y= mx + b

where

m is the slope

b is the y-intercept

Given the coordinate points on a line (3, 2) and (-1, -1)

Slope = -1-2/-1-3

Slope = 3/4

Determine the y-intercept

2 = 3/4(3) + b
2 = 9/4 + b

b = 2 - 9/4

b = -1/4

The required equation of the line passing the coordinates will be y = 3/4x - 1/4

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What is the solution to this system of equations 5x+2y=29
X+4y=13

Answers

Answer:

(5, 2 )

Step-by-step explanation:

5x + 2y = 29 → (1)

x + 4y = 13 → (2)

multiplying (1) by - 2 and adding to (2) will eliminate y

- 10x - 4y = - 58 → (3)

add (2) and (3) term by term to eliminate y

- 9x + 0 = - 45

- 9x = - 45 ( divide both sides by - 9 )

x = 5

substitute x = 5 into either of the 2 equations and solve for y

substituting into (2)

5 + 4y = 13 ( subtract 5 from both sides )

4y = 8 ( divide both sides by 4 )

y = 2

solution is (5, 2 )

The driving distance from Seattle to Portland is 175 miles. Your car gets 25 miles per gallon. If gasoline is $2.80 per gallon, how much will the round trip from Seattle to Portland and back cost in dollars?

Answers

Answer:

$980

Step-by-step explanation:

Given the cost of gasoline = $2.80/mile

Total Distance = 175miles x 2 (Back and forth)

= 350 miles

Total Cost = Cost of gasoline x Total Distance =

= $2.80 x 350

= $980

The total cost of the trip from Seattle to Portland and back cost in dollars will be;

⇒ $250

What is an expression?

Mathematical expression is defined as the collection of the numbers variables and functions by using operations like addition, subtraction, multiplication, and division.

Given that;

The driving distance from Seattle to Portland is 175 miles.

Your car gets 25 miles per gallon and the cost of gasoline is $2.80 per gallon.

Now,

Since, The driving distance from Seattle to Portland is 175 miles.

Hence, The total distance from Seattle to Portland and back = 175 + 175

                                                                                            = 350 miles

And, Your car gets 25 miles per gallon and the cost of gasoline is $2.80 per gallon.

Hence, The cost of gallon = 350/25 x $2.50

                                        = 100 x $2.50

                                        = $250

Thus, The total cost of the trip from Seattle to Portland and back cost in dollars will be;

⇒ $250

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The line whose equation is y=4x+2 has a y-intercept with coordinates

Answers

Answer: 2xy

Step-by-step explanation: 2xy is the answer bra

easy:
Clara buy: 300 apples, 74 potato, 15 eggs e 2 phone.
how many things did he buy in all?
Hard:
There are 92 boys in a school, the girl 100.How many more girl are there than boys?​

Answers

Answer:

easy = 391 items

hard = there are 8 more girls than there are boys

1)391
2)8

Those are the answers :)

The ratio of the number of fiction book is 9:4, the different between the number of fiction and non fiction is 245

Answers

Answer:

Step-by-step explanation:

The ratio of the number of fiction books is 9:4

 the difference between the number of fiction and nonfictionn is 245

so if the number of fiction books = 9x

then the number of nonfiction books = 4x

then difference = 9x-4x = 5x

the difference is given 245

then 5x= 245

x=[tex]\frac{245}{5}[/tex]=49

number of fiction books =49×9=441

number of nonfiction books =49×4=196

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2 ft
4.5 ft
6 ft
A) 38 cubic feet
B) 54 cubic feet
C)
66 cubic feet
D) 125 cubic feet
What is the volume?

Answers

Answer:

B

Step-by-step explanation:We know Volume = (a*b*c)

Answer:

B) 54 cubic feet

Step-by-step explanation:

definition of Identity property, Association property and communicative property please answer!​

Answers

Answer:

09

Step-by-step explanation:

07

8 cm
6 cm
2 cm
Find the surface area of the rectangular prism.
Surface Area = [?]cm²

Answers

Answer:

152cm²

Step-by-step explanation:

math and stuff and things


Which transformations will produce similar, but not congruent, figures?
Select each correct answer.
Square ABCD is dilated by a scale factor of and then translated 1 unit right to form square A” B" C"D"
Square ABCD is translated 8 units right and 8 units up and then reflected across the y-axis to form
square A"B" C"D"
Square ABCD is reflected across the x-axis and then dilated by a scale factor of 2 to form square A" B" C"D"
Square ABCD is rotated 270" clockwise and then dilated by a scale factor of to form square A" B”C” D”

Answers

Answer:

The correct answers are A B D

Step-by-step explanation:

hope this helped!

What is the product? Assume x≥0.

(√3x + √5)√15x+2√30)

A. 3x√√5 +3√165x+10√√6
B. 3x√5+6√10x +5√3x +10√6
C. 3x√√5+10√6
D. 6√3x+10√6

Answers

The product of (√3x + √5)(√15x+2√30) assuming x ≥ 0 is 3√5x² + 6√10x + 5√3x + 10√6

What is the product of the expression?

It follows from the task content that the expression given whose product is to be evaluated is;

(√3x + √5)(√15x+2√30)

Hence, by multiplying the terms with each other accordingly; we have;

= (√45x² + 2√90x + √75x + 2√150)

= 3√5x² + 2√90x + √75x + 2√150

= 3√5x² + 2×3√10x + √75x + 2√150

= 3√5x² + 2×3√10x + 5√3x + 2√150

= 3√5x² + 2×3√10x + 5√3x + 10√6

= 3√5x² + 6√10x + 5√3x + 10√6

Ultimately, the product of the expression is; 3√5x² + 6√10x + 5√3x + 10√6

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What value represents the vertical translation from the graph of the parent function f(x)=x² to the graph of the function
g(x)=(x+5)2+3?
-5
-3
O
3
O5

Answers

The value is 3 which represents the vertical translation from the graph of the parent function f(x)=x² option third 3 is correct.

What is a function?

It is defined as a special type of relationship, and they have a predefined domain and range according to the function every value in the domain is related to exactly one value in the range.

We have a function:

f(x) = x²

The above function is a parent function.

The translation: vertical translation from the graph of the parent function.

F(x) → f(x) + 3

F(x) = x² + 3

The above function will shift vertical up by 3 units.

Thus, the value is 3 which represents the vertical translation from the graph of the parent function f(x)=x² option third 3 is correct.

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curved surface area of a cone = Trl, where r is the
radius and is the slant height.
The ice cream cone below is made from a piece of wafer.
Work out the area of wafer required to make the ice
cream cone.
Give your answer to 1 d.p.
2 cm
9 cm

Answers

The area of wafer required to make the ice cream cone 68.75 cm²

What is Area?

The area is the amount of space within the perimeter of a 2D shape. It is measured in square units, such as cm², m², etc.

Given:

r= 2cm, l=9 cm

Surface area,

=πr(l +r)

=3.14*2(9 + 2)

= 6.25*11

=68.75 cm²

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Which is the graph of 2x - 4y > 6?
-4 -2
2
-2
2
RUTA
4-2
414
2
O
W
4 -4-2
414
2
-2
O
2
RY
4
-2
2
211

Answers

Answer:

  (d)  see attached

Step-by-step explanation:

There are a couple of quick checks you can do to identify the correct graph.

__

shading and line style

Find a variable with a positive coefficient, and write that in the given relation to the inequality symbol:

  x >

This tells you ...

shading is to the right of the line (where x-values are greater)the line is dashed (the = case is not included)location of the line

The x-coefficient is a factor of the constant, so the x-intercept of the boundary line is easily found. Set y=0, and you have ...

  2x = 6

  x = 3

The boundary line you're looking for has an x-intercept at x=3.

__

The correct graph is shown in the attachment.

Solve the equation -8 = -3 - 6 cube root x^2

a. 0.76, -0.76
b. 4.98
c. 3.87
d. 1.53, -1.53

Answers

Answer:

0.76

Step-by-step explanation:

-8+3=-6x^(2/3)

-5=-6 x^(2/3)

-5/-6=x^(2/3)

(2/3)√{5/6}=x

0.76=x

x=0.76

A 3-column table with 3 rows. Column 1 is labeled Unit Fraction with entries StartFraction 1 Over 10 EndFraction, one-fourth, c. Column 2 is labeled Fraction with 100 in the denominator with entries StartFraction 10 Over 100 EndFraction, b, StartFraction 50 Over 100 EndFraction. Column 3 is labeled Percent with entries a, 25 percent, 50 percent.
Complete the table by finding the missing equivalent form for each row.

a =
b =
c =

Answers

The missing equivalent forms are: a = 10%,  b = 25/100 and c = 1/2

Complete question

Unit Fraction   Fraction with 100 in denominator      Percent

1/10                              10/100                                             a

1/4                                  b                                                  25%

c                                  50/100                                           50%

Complete the table by finding the missing equivalent form for each row.

How to determine the missing equivalent forms?

From the above table, we have the following equations

a = 10/100

b = 25%

c = 50/100

The variable a must be in percentage.

So, we have:

a = 10/100

Express as percentage

a = 10%

The variable b must be a fraction with 100 in denominator

So, we have:

b = 25%

Express as fraction

b = 25/100

The variable b must be a unit fraction

So, we have:

c = 50/100

Divide the fraction by 50/50

c = 1/2

Hence, the missing equivalent forms are:

a = 10%,  b = 25/100 and c = 1/2

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Consider the matrix [tex]A_{4x4}, det(A) = -2[/tex]

Show that the following is true or false:


[tex]det(adj(2A^{-1}) =-2^{9}[/tex]

Answers

We found a counterexample, so the statement is false.

Is the statement true?

Let's use the matrix:

[tex]\left[\begin{array}{cccc}-2&0&0&0\\0&1&0&0\\0&0&1&0\\ 0&0&0&1 \end{array}\right][/tex]

This is a 4x4 matrix with determinant equal to -2.

The inverse matrix is:

[tex]\left[\begin{array}{cccc}1/2&0&0&0\\0&-1&0&0\\0&0&-1&0\\ 0&0&0&-1 \end{array}\right][/tex]

If we multiply it by 2, we get:

[tex]\left[\begin{array}{cccc}1&0&0&0\\0&-2&0&0\\0&0&-2&0\\ 0&0&0&-2 \end{array}\right][/tex]

The adjoint of that is the original matrix, actually:

[tex]\left[\begin{array}{cccc}-2&0&0&0\\0&1&0&0\\0&0&1&0\\ 0&0&0&1 \end{array}\right][/tex]

Which we already know, has a determinant of -2.

So the statement is false, as we found a counterexample.

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Which of the following is the graph of y= e^x + 1?

Answers

Answer + Step-by-step explanation:

y= e^x + 1

+ 1 will shift the graph up 1In the natural exponential function, eˣ = e power x, we employ e. In the eˣ function, the tangent line's slope to any point on the graph is equal to that point's y-coordinate. The sequence we employ to calculate the value of e is (1 + 1/n)

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Q5
The following are data from an independent measures experiment comparing
two treatment conditions:
Treatment 1
n=8
M = 8
SS=104
Treatment
n=8
M = 14
SS = 120
a. Do these data indicate a significant difference between the two
treatments?
b. Compute r2 and interpret the size of the treatment effect.

Answers

Answer:

A 2kg block is moved a long a level floor by a horizontal force of 20N if the coefficient of sliding friction is 0.4

what is the acceleration of the blove

Determine the number of zeros of the polynomial function. f(x) = x^3 + 7x^2 + 2

Answers

Answer:

  3

Step-by-step explanation:

The fundamental theorem of algebra tells you the number of zeros is equal to the degree of the polynomial.

__

application

The given degree-3 polynomial has 3 zeros.

__

Additional comment

Descarte's rule of signs tells you the absence of sign changes among the coefficients means that there are no positive real roots. Changing the sign of the one odd-degree term gives one sign change, so there is one negative real root. The other two zeros are complex.

  one negative real zero, and two complex zeros

A graph confirms that the only real zero is negative and irrational, about -7.04.

X^2=50 where x is a real number

Answers

The value of x in the given expression x² = 50 is 5√2

Data obtained from the questionx² = 50Value of x =?

How to determine the value of x

x² = 50

Thake the square root of both sides

x = √50

Recall

√50 = √(25 × 2) = 5√2

Thus,

x = √50

x = 5√2

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The graphs of exponential functions f and g are shown on the coordinate plane below.

Answers

Answer:

-5

Step-by-step explanation:

Since g(x) is f(x) shifted 5 units down, g(x) = f(x) -5. Therefore k = -5

Bella wants to know how long her dog is. She measure its body and finds that it is 54 cm long. Then she measures the tail and find it is 34 cm long. How long is Bella's dog from body to tail?

Answers

Answer:

88 cm

Step-by-step explanation:

body to tail = length of body + length of tail

body to tail = 54 cm + 34 cm

body to tail = 88 cm

What is the value of x?

Answers

The value of x in the segment is 3

How to determine the value of x?

Using the secant and segment theorem, we have:

x * (x + 21) = (x + 1) * (x + 1 + 14)

Evaluate the sum

x * (x + 21) = (x + 1) * (x + 15)

Expand

x^2 + 21x = x^2 + 15x + x + 15

Subtract x^2 from both sides

21x = 15x + x + 15

Evaluate the like terms

5x = 15

Divide both sides by 5

x = 3

Hence, the value of x is 3

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how is -x^6+7x^5 considered a sixth degree binomial?

Answers

Answer:

Polynomial, 6. Constant. The highest value of the exponent in the expression is known as the Degree of Polynomial. The degree of a polynomial is the largest exponent. It is also known as an order of the polynomial. While finding the degree of the polynomial, the polynomial powers of the variables should be either in ascending or descending order.

Step-by-step explanation:

A term is defined as a part of an equation separated by a +/- operation. Because there is a + operation separating two terms (-x^6 and 7x^5), the expression is a binomial, meaning the expression has two terms.

The highest exponent or degree, present in the expression is to the power of 6. Therefore, the expression is in the sixth degree.

Taken together, the expression is a sixth-degree binomial.

Philip ran out of time while taking a multiple-choice test and plans to guess the last 4 questions. Each question has 5 possible choices, one of which is correct. Let X=X=X, equal the number of answers Philip correctly guesses in the last 444 questions. Assume that the results of his guesses are independent.
What is the probability that he answers exactly 1 question correctly in the last 4 questions?

Answers

Using the binomial distribution, it is found that there is a 0.4096 = 40.96% probability that he answers exactly 1 question correctly in the last 4 questions.

What is the binomial distribution formula?

The formula is:

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]

The parameters are:

x is the number of successes.n is the number of trials.p is the probability of a success on a single trial.

Considering that there are 4 questions, and each has 5 choices, the parameters are given as follows:

n = 4, p = 1/5 = 0.2.

The probability that he answers exactly 1 question correctly in the last 4 questions is P(X = 1), hence:

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

[tex]P(X = 1) = C_{4,1}.(0.2)^{1}.(0.8)^{3} = 0.4096[/tex]

0.4096 = 40.96% probability that he answers exactly 1 question correctly in the last 4 questions.

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What is the solution set of -xl = -10?

Answers

No solution since absolute value can't be equal to negative numbers

PLEASE GIVE BRAINLIEST

No solution since it can’t be equal to negative numbers
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