-3+-4^2 divided by 2

Arithmetic Sequence

'nth' term of each

i)n^2+2n

ii) n^2- 2n​

1) Sum of first n terms = n² + 2n

We know that,

Sum of first n terms = n/2 * [ a + l ]

Where,

a is first term

l is nth or last term.

Substitute n = 1 to find the sum of first 1 terms i.e., first term (a) of the AP.

→ S₁ = a = (1)² + 2(1)

→ a = 1 + 2

→ a = 3

Hence,

→ n/2 * [ a + l ] = n² + 2n

→ a + l = n(n + 2) * 2/n

→ a + l = 2n + 4

→ l = 2n + 4 - a

→ l = 2n + 4 - 3

→ l = 2n + 1

Hence, the nth term is 2n + 1.

2)S(n) = n² - 2n

→ S₁ = a = (1)² - 2(1)

→ a = - 1

Hence,

→ n/2 * [ - 1 + l ] = n² - 2n

→ l - 1 = n(n - 2) * 2/n

→ l - 1 = 2n - 4

→ l = 2n - 4 + 1

→ l = 2n - 3

Hence, the nth term is 2n - 3.

I hope it will help you.

Regards.

Step-by-step explanation:

Series

The series of a sequence is the sum of the sequence to a certain number of terms. It is often written as Sn. So if the sequence is 2, 4, 6, 8, 10, ... , the sum to 3 terms = S3 = 2 + 4 + 6 = 12.

The Sigma Notation

The Greek capital sigma, written S, is usually used to represent the sum of a sequence. This is best explained using an example:

This means replace the r in the expression by 1 and write down what you get. Then replace r by 2 and write down what you get. Keep doing this until you get to 4, since this is the number above the S. Now add up all of the term that you have written down.

This sum is therefore equal to 3×1 + 3×2 + 3×3 + 3×4 = 3 + 6 + 9 + 12 = 30.

3

S 3r + 2

r = 1

This is equal to:

(3×1 + 2) + (3×2 + 2) + (3×3 + 2) = 24 .

The General Case

n

S Ur

r = 1

This is the general case. For the sequence Ur, this means the sum of the terms obtained by substituting in 1, 2, 3,... up to and including n in turn for r in Ur. In the above example, Ur = 3r + 2 and n = 3.

Arithmetic Progressions

An arithmetic progression is a sequence where each term is a certain number larger than the previous term. The terms in the sequence are said to increase by a common difference, d.

For example: 3, 5, 7, 9, 11, is an arithmetic progression where d = 2. The nth term of this sequence is 2n + 1 .

In general, the nth term of an arithmetic progression, with first term a and common difference d, is: a + (n - 1)d . So for the sequence 3, 5, 7, 9, ... Un = 3 + 2(n - 1) = 2n + 1, which we already knew.

The sum to n terms of an arithmetic progression

This is given by:

Sn = ½ n [ 2a + (n - 1)d ]

You may need to be able to prove this formula. It is derived as follows:

The sum to n terms is given by:

Sn = a + (a + d) + (a + 2d) + … + (a + (n – 1)d) (1)

If we write this out backwards, we get:

Sn = (a + (n – 1)d) + (a + (n – 2)d) + … + a (2)

Now let’s add (1) and (2):

2Sn = [2a + (n – 1)d] + [2a + (n – 1)d] + … + [2a + (n – 1)d]

So Sn = ½ n [2a + (n – 1)d]

Example

Sum the first 20 terms of the sequence: 1, 3, 5, 7, 9, ... (i.e. the first 20 odd numbers).

S20 = ½ (20) [ 2 × 1 + (20 - 1)×2 ]

= 10[ 2 + 19 × 2]

= 10[ 40 ]

= 400

Geometric Progressions

A geometric progression is a sequence where each term is r times larger than the previous term. r is known as the common ratio of the sequence. The nth term of a geometric progression, where a is the first term and r is the common ratio, is:

arn-1

For example, in the following geometric progression, the first term is 1, and the common ratio is 2:

1, 2, 4, 8, 16, ...

The nth term is therefore 2n-1

The sum of a geometric progression

The sum of the first n terms of a geometric progression is:

a(1 - rn )

1 – r

We can prove this as follows:

Sn = a + ar + ar2 + … + arn-1 (1)

Multiplying by r:

rSn = ar + ar2 + … + arn (2)

(1) – (2) gives us:

Sn(1 – r) = a – arn (since all the other terms cancel)

And so we get the formula above if we divide through by 1 – r .

Example

What is the sum of the first 5 terms of the following geometric progression: 2, 4, 8, 16, 32 ?

S5 = 2( 1 - 25)

1 - 2

= 2( 1 - 32)

-1

= 62

The sum to infinity of a geometric progression

In geometric progressions where |r| < 1 (in other words where r is less than 1 and greater than –1), the sum of the sequence as n tends to infinity approaches a value. In other words, if you keep adding together the terms of the sequence forever, you will get a finite value. This value is equal to:

a

1 – r

Example

Find the sum to infinity of the following sequence:

1 , 1 , 1 ,

1

,

1

,

1

, ...

2 4 8 16 32 64

Here, a = 1/2 and r = 1/2

Therefore, the sum to infinity is 0.5/0.5 = 1 .

So every time you add another term to the above sequence, the result gets closer and closer to 1.

Harder Example

The first, second and fifth terms of an arithmetic progression are the first three terms of a geometric progression. The third term of the arithmetic progression is 5. Find the 2 possible values for the fourth term of the geometric progression.

The first term of the arithmetic progression is: a

The second term is: a + d

The fifth term is: a + 4d

So the first three terms of the geometric progression are a, a + d and a + 4d .

In a geometric progression, there is a common ratio. So the ratio of the second term to the first term is equal to the ratio of the third term to the second term. So:

a + d = a + 4d

a a + d

(a + d)(a + d) = a(a + 4d)

a² + 2ad + d² = a² + 4ad

d² - 2ad = 0

d(d - 2a) = 0

therefore d = 0 or d = 2a

The common ratio of the geometric progression, r, is equal to (a + d)/a

Therefore, if d = 0, r = 1

If d = 2a, r = 3a/a = 3

So the common ratio of the geometric progression is either 1 or 3 .

Answer:

4,3,0.5 youre welcome, good Luckk : )

Answer

Option D

Step-by-step explanation

For further help (727) 335-8234

The first step of indirect proof of the conditional below

If x2 = 25, then 5’2= 25 and x = 5 is assume 5² = 25.

Option B is the correct answer.

An equation is a mathematical statement that is made up of two expressions connected by an equal sign.

We have,

Conditions:

x² = 25 then 5² = 25 and x = 5

If we have to prove the above conditions indirectly, we have to prove that x² = 25 using the conditions 5² = 25 and x = 5.

So,

We have to assume,

Step 1:

5² = 25

Step 2:

x = 5

Step 3:

x² = 25

Thus,

The first step of indirect proof of the conditional below

If x2 = 25, then 5’2= 25 and x = 5 is assume 5² = 25.

Option B is the correct answer.

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Answer:

...infinity cubic inches?

Step-by-step explanation:

Answer: -20/3

Step-by-step explanation:

Answer: It equals -8/3

Answer:

Length = 4 times width

Area = length * width

=(4w)w

=4w²

So 4w²=1024 cm² (given)

w²=1024/4=256

w=√(256 cm²)

=16 cm (reject negative value of square-root)

Step-by-step explanation:

Hope this helps you

Crown me as brainliest:)

Answer:

Step-by-step explanation:

7/8 is 63/72

5/12 is 25/60

4/18 is 8/36

Answer:

54

Step-by-step explanation:

126+54=180

Answer:

1, 3, 7, 21

p-by-step explanation:

Answer:

Step-by-step explanation:

1st one is 62.5 kilogramic meter

2nd one is 1 kilo kilogram/cubic meter

Step-by-step explanation:

1)First calculate the volume

v=Pir²h

v=3.15×4²×4

v=201mm³

p=m/v

p=0.250/0.201

p=1.24Kg/m³

2)v=3/4pi r³

v=3/4×3.14×2³

v=33.5m³

p=m/v

p=2/33.5

p=0.0597kg/m³

Answer:

I think that Nick is correct because you are going to have to make your answer positive and when you do the two fractions -4/9 + -6/9 are going to be   6/9 + 4/9 and there is already a addition sign in the last problem we are just going to keep it there. And when we add we get 10/9 or 1 1/9

If i get it wrong please don't hate im just in 7 grade ok :(

Answer:

Solution given:

Gobriella is correct.

Nick change - to + in second line.

Answer:

What are the stores & the data?

Answer:

1/4

Step-by-step explanation:

Answer:

6 2/5=x

Step-by-step explanation:

Answer:

x is less-than-or-equal to 3

Step-by-step explanation:

4(3)+6 =18

Answer: G=7.12

Step-by-step explanation: 25g-175=3 add 175 to both side which makes the equation 25g=178 and divide 178 by 25 which gives you 7.12

Answer:

g=178/25

Step-by-step explanation:

Step 1: 25(g-7)/25=3/25

Step2: g-7=3/25

Step 3: g-7+7=3/25 + 7

Answer: g=178/25

Decimal form would be g=7.12

Answer:

Option 2

Step-by-step explanation:

The length is unknown, so it is l for now. A rectangle has 2 lengths and widths, so the values are 2w and 2l. The sum of 2w and 2l have to be greater than or equal to 776, so the answer is option 2. If you solve the inequality, the length is equal to or greater than 355

Answer:

60

Step-by-step explanation:

(10)(-2)(-3) = ?

The minuses cancel out each other

10*2*3 --> 20* 3

Simplified Math

60

Sum

Answer:

w≤-7

Step-by-step explanation:

No more than means it has to be -7 or less so w is no more than -7 is w≤-7

Hope this helps!

Answer:

I agree if that's what you say it mean

Answer:

hence the ans of g(-3)=12

Answer:

11.25

Step-by-step explanation:

Multiply 4.5 by the reciprocal of 2/5, which is 5/2. You will then get 11.25. Hope this helped :)

Total number of cups of water needed to prepare 5 cups of rice are 11.25.

What is mean by Ratio?

A ratio indicates how many times one number contain in another number. The ratio of two number is written as x : y, which is equivalent to x/y.

Where, x and y are individual amount of two quantities.

And, Total quantity gives after combine as x + y.

Given that;

When rice is prepared, the amount of rice varies directly as the amount of water required.

And, 2 cups of rice requires 4.5 cups of water.

Now,

Since, 2 cups of rice requires 4.5 cups of water.

Hence, For 1 cup of rice, number of cups of water = 4.5 / 2

                                                                             = 2.25

So, For 5 cups of rice, number of cups of water = 5 x 2.25

                                                                          = 11.25

Thus, Total number of cups of water needed to prepare 5 cups of rice are 11.25.

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Answer:

Step-by-step explanation:

Answer:

I think 2 and 3

Step-by-step explanation:

Answer:

3,125; 24.5p

Step-by-step explanation:

Answer:

3125-24.5p       and 2,978

Step-by-step explanation:

a.The expected number of emails is 12

b. The variance and the standard deviation is 7.200 and 2.683

Given that

P = 0.40 and n = 30

a)

The expected value of received e-mails is

= n × p

= 30 × 0.4

= 12  

b)

The variance of emails received is

= n × p × (1 - p)

= 30 × 0.4 × 0.6

= 7.200

Now

The standard deviation of emails received is

= sqrt(variance)

= 2.683

We simply applied the above formula

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Answer:

−2(−x+4) − 3x+2= −5 what is x? Well i might be wrong but i think its 2x

Step-by-step explanation:

PEMDAS USE THAT METHOD

Answer: x=-1

Step-by-step explanation:

Answer: the answer is 1300 hope this helps you

Step-by-step explanation: