Show that the sum of the first 2n natural numbers is n(2n+1)

Not really sure if there’s a typo in my book or not

Answers

Answer 1

Answer:

This sum is the sum of an arithmetic sequence.  There is a formula for the sum of an arithmetic sequence which can be looked up or derived by a variety of means.

A nice approach for this sequence is the following.  Notice  that the sum of first and last number in the sequence is the same as the sum of the second and second last, and also the same as the sum of the third and third last, and so on.

There are n of these pairs.  So the desired sum is n x (first number + last number).   But the first number is 1 and the last on is 2n.   Thus the desired sum is n(1 + 2n).

Hope this helps!!

Mark Brainleast!!!!!!!!!!!

Answer 2

Consider the set {1, 2, 3, 4, ..., m} where m is some natural number, i.e. a positive whole number.

Now let's say we wanted to add everything in that set.

What we can do is write out the terms

1, 2, 3, 4, ..., m

then just underneath, we write the reverse of that set

m, ..., 4, 3, 2, 1

Here's an example of what I mean. I'll use m = 7

[tex]\begin{array}{|c|c|c|c|c|c|c|} \cline{1-7}1 & 2 & 3 & 4 & 5 & 6 & 7\\\cline{1-7}7 & 6 & 5 & 4 & 3 & 2 & 1\\\cline{1-7}\end{array}[/tex]

For each column, add straight down

The third row will be nothing but 8's

[tex]\begin{array}{|c|c|c|c|c|c|c|} \cline{1-7}1 & 2 & 3 & 4 & 5 & 6 & 7\\\cline{1-7}7 & 6 & 5 & 4 & 3 & 2 & 1\\\cline{1-7}8 & 8 & 8 & 8 & 8 & 8 & 8\\\cline{1-7}\end{array}[/tex]

We can see there are seven copies of '8' being added here, so the sum of all the numbers in the set {1,2,3,4,5,6,7} is 8*7 = 56. But wait, we double-counted each item when we formed the second row. So we must divide by 2 to fix the double-counting error.

Therefore, 1+2+3+4+5+6+7 = 56/2 = 28 instead.

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

That previous example showed that adding from 1 to 7 means we have 7 copies of (1+7). In other words, 7 copies of 8 being added.

We could write that as 7(1+7)

Then divide that by 2 to fix the double-counting error.

We have 7(1+7)/2

Now imagine that we applied all of what was mentioned to the set {1,2,3,4,5,6,7,8}. Instead of 7's, we use 8's this time to get 8(1+8)/2

Then we can extend it out to the set {1,2,3,4,..., m} and we get the formula m(1+m)/2

We have m copies of (1+m) being added; hence the m(1+m). Don't forget to divide by 2 to fix the double-counting error.

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

The key takeaway here is that summing 1+2+3+4+...+m gets us m(1+m)/2

In this case, m = 2n because we want the first 2n natural numbers.

Therefore,

m(1+m)/2

2n(1+2n)/2

n(1+2n)

n(2n+1)

represents the sum 1+2+3+...+n+...+2n

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

Try out a value like n = 5 to find that 2n = 2*5 = 10, and,

1+2+3+4+5+6+7+8+9+10 = 55

also

n(2n+1) = 5(2*5+1) = 5*(11) = 55

Showing that the formula works for n = 5. I'll let you try other values of n.


Related Questions

64.89% of 407.68cm

Give your answer rounded to 2dp

Answers

Answer: 264.54cm

Step-by-step explanation:

407.68x0.6489=264.543552264.543552 rounded to 2 decimal points is 264.54

A recipe for muffins calls for 1 1 over 3 cups of milk. a recipe for bread calls 2 over 3 cup of milk how much more milk is needed for the muffin recipe than the bread recipe

Answers

Answer:

The Muffin Recipe calls for 3 more cups of Milk than the Bread Recipe.

Step-by-step explanation:

11/3=

3[tex]\frac{2}{3}[/tex]

2/3

We can see that the difference is GREAT. So, now, let's subtract.

[tex]3\frac{2}{3} -\frac{2}{3} =3[/tex]

So hence, the Muffin Recipe calls for 3 more cups of Milk than the Bread Recipe!

----------------------------------------------------------------------------------------------------------"The beautiful thing about learning is that no one can take it away from you!"

B.B.King

Thanks!

Have a great night!

~ms115~

:D

The muffin recipe requires 2/3 cup more milk than the bread recipe.

What is subtraction?

Subtraction is a mathematical operation. Which is used to remove terms or objects in the expression.

To find out how much more milk is needed for the muffin recipe than the bread recipe,

we need to calculate the difference between the amount of milk required for each recipe.

The muffin recipe calls for 1 1/3 cups of milk, which is equivalent to 4/3 cups of milk.

The bread recipe calls for 2/3 cup of milk.

To find the difference between the two amounts of milk, we can subtract the milk required for the bread recipe from the milk required for the muffin recipe:

4/3 - 2/3 = 2/3

Therefore, 2/3 is the required fraction.

To learn more about subtraction;

https://brainly.com/question/2346316

#SPJ2

when I think of a number, double it , then add seven , I get 23. Determine the number I first thought of

Answers

Answer:

8

Step-by-step explanation:

2x + 7 = 23

2x = 16

X = 8

i do not know this answer

Answers

Answer: awnser is m= 1/6

Step-by-step explanation: m = add the terms which is  -1 -5m-4+6 m= 1-5m

step 2 then rerange the terms  to m= 1-5m to m = 5m + 1

step 3  add 5m to both sides m= -5m+1 to m + 5m= -5m + 1  + 5m

step 4  simplify and combine like terms 6m= 1

step 5 divide both sides by the same factor 6m= 1  6m/6 =  1/6

step 6 simplify Cancel terms that are in both the numerator and denominator so it is m= 1/6 is the correct awnser mark me brainliest please

2Answer: the answer is -5m+2
Step-by-step explanation: here are the steps .
-5m-4+6
-5m+2
Negative four plus six gives positive 2 because you will make 6 minus 4 and it will tale the sign of the bigger number so it positive two ( 2 ) so negative 5m plus two . -5m+2
HOPE IT HELPS. PLEASE GIVE BRAINLIEST. THANKS.

(100 POINTS AND BRAINLIEST) Please use the answers that are given. Using the following data, calculate the mean absolute deviation
What is the mean absolute deviation for these data?
A: 9
B: 5.4
C: 5
D: 2.6

Answers

Answer:

There isn't any data, maybe you could put the rest of the question in the comment area.

Please help will give brainliest

Which of the following are tangent to circle A? Select all that apply
see picture

Answers

Answer:

RS RT ST

Step-by-step explanation:

This is due to the facts that tangency means having contact at a single point or along a line without crossing. so the first 3 options are correct

Find the area of the following triangle. Show each of the math steps that you use to find the area. Then explain how to go about finding the area of this particular triangle (explain each one of the steps that you showed with your math).

Answers

Right angled triangle

Base=B=2.4cmHeight=H=1.8cm

Area:-

[tex]\\ \rm\rightarrowtail \dfrac{1}{2}BH[/tex]

[tex]\\ \rm\rightarrowtail \dfrac{1}{2}(2.4)(1.8)[/tex]

[tex]\\ \rm\rightarrowtail 1.2(1.8)[/tex]

[tex]\\ \rm\rightarrowtail 2.16cm^2[/tex]

What is the measure of each angle in the circle?

40°
60°
45°
36°

Answers

Answer:

i think it would be 45

hope im right

if not i can change it

Step-by-step explanation:

Answer:

45°

Step-by-step explanation:

The circle is divided into 8 equal arcs, each arc measuring an angle of:

360/8 = 45°

Hope this helps

Please Help!!! Will Mark Brainliest!

Answers

Step-by-step explanation:

from my side it's blury, try to send it again

Abebi surveyed how many miles the students in her Algebra 1 class travel to get to school, and ended up with the following set of data: 4.75, 2.25, 3, 3.5, 1.75, 2.25, 1.5, 5, 4.5, 2.25, 2, 3, 2.65, 4.8, 3.5\

Match the measures of central tendency to the correct values.

Hint:

MEAN = Sum of the data/# of data values

MEDIAN = middle data value when values are listed least to greatest

MODE = value appearing the most times

RANGE = difference between the largest and smallest values

Answers

Answer:

Mean: 3.1

Median: 3

Mode: 2.25 appears 3 times

Range: 5 - 1.5 = 3.5

Mean = (4.75+2.25+3+3.5+1.75+2.25+1.5+5+4.5+2.25+2+3+2.65+4.8+3.5)/16

= 3.56625

Median = 3.50

Mode = 2.25

Range = 9.10

This is a 30-60-90 triangle.
What is the measure of x?
Rationalize the denominator.
[?]
х
X=
7

Answers

Answer:

x = [tex]\frac{2\sqrt{21}}{3}[/tex]

Step-by-step explanation:

For a 30-60-90 triangle:

Short leg = sLong leg = s√3Hypotenuse = 2s

Thus:

Short leg = √7/√3 = (√21)/3Long leg = √7Hypotenuse = x = 2(√21)/3

Answer:

2 21 3

Step-by-step explanation:

How would you expand log412 so that it can be evaluated, given log43 ≈ 0.792? Log Subscript 4 Baseline 3 times log Subscript 4 Baseline 4 StartRoot a squared + b squared EndRoot log 3 + log 4 log Subscript 4 Baseline 3 + log Subscript 4 Baseline 4 log 3 times log 4

Answers

Answer: log412 = 1.792

Step-by-step explanation:

log412 = log4(3 x 4)

log4(3 x 4) = log4(3) + log4(4)

log4(4) = 1

log4(3) = .792

1 + .792 = 1.792

log412 = 1.792

Evaluate (2 minus 5 i) (p + q) (i) when p = 2 and q = 5 i.
29 i

29 i - 20

- 21 i

29

Answers

(2 - 5i) ( 2 + 5i) (i)
(4 + 10i -10i -25) (i)
(4 - 25) (i)
-21i

Find the volume of a cone that has a diameter of 14 feet and a height of 11 feet. Use 3.14 for pi

Answers

Answer:

564.15 cubic ft

[tex] \: [/tex]

Step-by-step explanation:

In the question, it is given that a cone has a diameter of 14 feet and a height of 11 feet and we have to find the volume of the cone.

[tex] \: [/tex]

To Find the volume of the cone, we must know this formula :

[tex] \\{\longrightarrow{ \qquad{\underline{\boxed {\pmb{\frak { Volume_{(cone) }= \dfrac{1}{3} \: \pi {r}^{2}h }}}}}}} \\ \\[/tex]

Where,

r refers to the radius of the cone. As the diameter is 14 ft, therefore the radius will 7 ft.

h refers to the height of the cone.

Now, we will substitute the values in the formula :

[tex] \\ {\longrightarrow{ \qquad{{ {\pmb{\sf { Volume_{(cone) }= \dfrac{1}{3} \times 3.14 \times {(7)}^{2} \times 11 }}}}}}} \\ \\[/tex]

[tex]{\longrightarrow{ \qquad{{ {\pmb{\sf { Volume_{(cone) }= \dfrac{1}{3} \times 3.14 \times 49 \times 11 }}}}}}} \\ \\[/tex]

[tex]{\longrightarrow{ \qquad{{ {\pmb{\sf { Volume_{(cone) }= \dfrac{1}{3} \times 3.14 \times 539 }}}}}}} \\ \\[/tex]

[tex]{\longrightarrow{ \qquad{{ {\pmb{\sf { Volume_{(cone) }= \dfrac{1}{3} \times 1692.46 }}}}}}} \\ \\[/tex]

[tex]{\longrightarrow{ \qquad{{ {\pmb{\sf { Volume_{(cone) }= \dfrac{1692.46}{3} }}}}}}} \\ \\[/tex]

[tex]{\longrightarrow{ \qquad{{ {\pmb{\sf { Volume_{(cone) }= \: \: \underline{ \boxed{ \frak{564.15 } }} }}}}}}} \: \: \bigstar \\ \\[/tex]

Therefore,

The volume of the cone is 564.15 ft³ .

Step-by-step explanation:

Given :-

Height of cone :- 11 feet Diameter of cone :- 14 feet , radius = 7 feet

To Find :-

Volume of cone

Solution:-

Formula for volume of cone = 1/3πr²h

putting the known values ,

Volume = 1/3×3.14×7²×11 cubic ft.

Volume = 564.15 cubic ft.

How would we add -3 + (-9) on the number line?

Answers

Answer:

-12

Step-by-step explanation:

1. Create an Equation

-3-9

2. Solve

-3-9 <=== subtract -3 and -9 together to get your answer

-12

3. Check

-12+3 <=== create this equation or this one ===> -12+9 to check if we calculated correctly

-12+3= -9 -12+9= -3

this shows the answer is corrrect

when you are adding a positive number we would go right but -9 isn’t a positive it’s a negative so we would go left on the number line

Q: Ribbon cost $1.44 for 3 m.
(1) What is the cost per meter?
(2) How much would 5 m of ribbon cost?
(3) How much ribbon could you buy for $12?

Answers

Answer:

1.44 divided by 3m will give $0.48/5 times 0.48 gives 2.412 times three divided by 1.44 gives$.25

Pls help !!!!!!!!!!!!!!!!!!!!!!!!!

Answers

Answer:

D. Rhombus.

Step-by-step explanation:

This will be a quadrilateral with 4 equal sides.

The oppsoite angles will be equal   but they will not be 90 degrees as each triangle of the 3 dimensional figure is an equilateral triangle.

Therfore the cross section is a rhombus.

What is the volume of the rectangular prism below in cubic inches?

Answers

Answer:

24

Step-by-step explanation:

The volume formula is all the dimensions multiplied together, or lengthxwidthxheight.

So, you do 1x1x2 which is 2 feet. HOWEVER, it is looking for CUBIC INCHES, not cubic FEET.

There are twelve inches in a foot so 2x12=24 inches.

prove it equals 1
(Tanx - Cotx) + Sinx.Cosx

Answers

Step-by-step explanation:

(sinx/cosx - cosx/sinx) + sinxcosx

sin²x - cos²x = 1

I can't prove

I only know sin²x + cos²x = 1 : )

Past experience shows that Mr.Reisman will have 3 left-handed students in ever class of 25 math students. If Mr.Reisman teaches 125 students in one day, what is the most likely total number of left-handed students in his classes?

Answers

Answer:

15 students

Step-by-step explanation:

125/25=5

5x3=15

Im so desperate
ms. davis sold $309.00 of books. at the end of the day, she earned $27.81 in commission for those sales. what is ms. davis' commission rate?​

question 8 options:

11%


9%


3.4%


2.81%

Answers

so Ms. Davis gets hmmm say "x" percent from sales as her commission, and we know she did in sales $309 and made $27.81.

if we take 309 to be the 100%, and x% of that is 27.81, what's "x"?

[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} 309 & 100\\ 27.81& x \end{array} \implies \cfrac{309}{27.81}=\cfrac{100}{x} \\\\\\ 309x=2781\implies x=\cfrac{2781}{309}\implies x=9[/tex]

a
С
b
60°
45°
Find a, b, and c.

Answers

Answer:

Step-by-step explanation:

The measures of the bases of a trapezoid are 14 and 20. What is the measure of the median of the trapezoid?

Answers

The median of the trapezoid is = 17

calculation of the median of a trapezoid

A trapezoid is a quadrilateral with one pair of opposite sides parallel. It has parallel sides which are known as the bases.

The base of the trapezoid(B1) =14

The base of the trapezoid (B2) = 20

To calculate the median = half the sum of the base of the trapezoid given.

Therefore,

14+20/2

34/2= 17

Therefore, the median of the trapezoid is = 17

Learn more about the trapezoid here:

https://brainly.com/question/1410008

What is the length of a car if the length on the scale madel car is 17 cm and the scale is 2 cm : 50 cm?

Answers

Answer:

x= 425

Step-by-step explanation:

In parallelogram crhs, the measure of angle c is 48.Find the measure of angle h?

Answers

Answer:

48°

Step-by-step explanation:

we know that opposite angle of parallelogram is equal

so,

angel C is equal to opposite angle H

H = 48

angle C = 48°

angle R = 132°

angle H = 48° (opposite of angle C)

angle S = 132°(opposite of angle R)

Mark me Brainiest please

express the following rational algebraic expression to its simple form.show your solution​

1. 25 ׳y³/ 75 ×⁴y⁴​

Answers

express the following rational algebraic expression to its simple form.show your solution

1. 25 ׳y³/ 75 ×⁴y⁴

Answer

1/3×y

PLEASE HELP WILL GIVE BRAINLIEST!!!!​

Answers

Answer:

Its The 3rd one you are correct in picture

Step-by-step explanation:

Element x decays radioactively with a half life of 12 minutes. if there are 580 grams
of element x, how long, to the nearest tenth of a minute, would it take the element to
decay to 68 grams?

Answers

Answer:

37.1

Step-by-step explanation:

37.1

Write and solve an equation to find the value of x

Answers

Answer:

Equation: x+90=7x

Answer: x=15

Step-by-step explanation:

By looking at the image, I can tell that both of those angles are vertical.

Vertical angles mean that both of the angles would be equal. Therefore, we can set x+90 = 7x

You then subtract x from both sides, leaving us with 90 = 6x

From there, divide both sides by 6 to isolate 6 to 1, and you are left with 15= x or x=15, giving you your answer and equation.

The value of x is 15.

What is an angle measure?

When two lines or rays intersect at a single point, an angle is created. The vertex is the term for the shared point. An angle measure in geometry is the length of the angle created by two rays or arms meeting at a common vertex.

Given that the two angle measures (x + 90)° and 7x°.

And both the angle measures are formed by opposite angles,

so,

x + 90 = 7x

Taking like terms to one side,

we get,

7x - x = 90

6x = 90

Divide by 6, and we get,

x = 90/6

x = 15

Therefore, x = 15°.

To learn more about the angle measure;

brainly.com/question/14684647

#SPJ7

What is the area of this figure?
18 ft
3 ft
15 ft
12 ft
9 ft
3 ft
square feet
Submit

Answers

Answer: Times it

Step-by-step explanation:

Answer:

90 square feet

Step-by-step explanation:

area of this figure = area of 1 rectangle + area of 2nd rectangle

= L×B + l × b

= 18 × 3 + 12 × 3

= 54 + 36

= 90 feet²

Other Questions
What are the preserved remains of organisms that provide evidence to support Darwins theory of evolution? fossils species extinctions populations Which of the following is NOT true about systems that cycle matter? A Living things play a role in the cycling of matter. B Matter changes form as it cycles. C Some matter is destroyed as it cycles through the environment. D Matter is constantly cycling through the environment using the similar triangles below, solve for x ! What does it mean when someone says when you left me you took a big piece of my heart with you? Prove: AB/CD =AC/CDCheck out the other post with this question to understand it fully. Work and effort scientifically the same thing True Or false Find the area of this parallelogram. A) 20 B) 24 C) 40 D) 60 The perimeter of arectangular poultry farm is 38 meter . if 3 meter subtracted from its length and 2 meter from its breadth , the length will be two times the breadth .find the area of the farm this is for my sister help her!!! i will Brainiest!!Which formation was created by glaciers in the last ice age?A. Mississippi RiverB. Great LakesC. Rocky MountainsD. Grand Canyon Coworker: Sometimes it is very hard to show deference to customers who verbally attack us. Given sinx=0.3, what is cosx? enter your answer as a decimal in the box. round only your final answer to the nearest hundredth. You are sitting at a coffee shop and you overhear a conversation at the next table. Two mothers are discussing their teen children and complaining about their behavior- erratic and irrational behavior, displaying little to no logic and reason. One says to the other, I just dont know who he is. You have just listened to the NPR article and learned about the Endocrine System. You offer the following advice Complete part (a) and part (b) given the following system of equations.x-y=1x + 3y =9Write your answer. Choose the appropriate form of the preterite or imperfect verb in each sentence:Por fin, yo (terminar) este (this) examen. please help will mark brainliest. How did Mendelssohn explore realms of fantasy in his A Midsummer Night's Dream overture? By depicting the sounds of mischievous woodland fairies. By writing music based on drug experiences. By depicting the sounds of a witches sabbath.By writing music based on his dreams. define eoonomic activities do what it says on the image As down the glen one Easter mornTo a city fair rode IThere armed lines of marching menIn squadrons passed me byNo pipe did humNo battle drum did sound its loud tattooBut the Angelus Bells o'er the Liffey swellsRang out in the foggy dewRight proudly high in Dublin townHung they out a flag of war'Twas better to die 'neath that Irish skyThan at Sulva or Sud-El-BarAnd from the plains of Royal MeathStrong men came hurrying throughWhile Brittania's Huns with their long range gunsSailed in through the foggy dewTheir bravest fell and the requiem bellRang mournfully and clearFor those who died that Eastertide in theSpringing of the yearWhile the world did gaze with deep amazeAt those fearless men but fewWho bore the fight that freedom's lightMight shine through the foggy dewAnd back through the glen, I rode againAnd my heart with grief was soreFor I parted then with valiant menWhom I never shall see n'moreBut to and fro in my dreams I goAnd I kneel and pray for youFor slavery fled, O glorious deadWhen you fell in the foggy dew WILL GIVE BRAINLIEST!!!!!!Your manager has been asked to speak to a community group about an upcoming development project that will be demolishing an old mall and building a mixed-use space with apartments, retail, and office spacea topic that has created some controversy in the community. Shes asked for your help in putting together her presentation. Do you think that a live or virtual presentation would be most effective? Why? What types of multimedia elements do you think would be most engaging? Why? Use the defined sets to answer the questions. assuming 0 is an even integer, which set is the complement to set b? which set is an empty set? which set would contain the subset e = {1, 3, 5, 7}?