The third term and an arithmetic sequence is 12 in the system is 16. If the first term is a1, what is the explicit formula for this sequence?

Answer:

130

ratio of woman to man is : 5/8

5/8×208=130

Answer:

130 women

Step-by-step explanation:

3 men to 5 women:

We can add the variable x:

3x + 5x = 208

8x = 208

x = 26

3 * 26 = 78 men,

5 * 26 = 130 women.

Answer:

Step-by-step explanation:

The progression of sums is ...

  1, 5, 15, 34, 65, ...

So, first differences are ...

  4, 10, 19, 31

Second differences are ...

  6, 9, 12, ...

Third differences are constant:

  3, 3, ...

This means the expression for Sn will be a cubic expression. If dn is the first of the n-th differences, then the equation can be written as ...

  Sn = S1 +(n -1)(d1 +(n -2)/2(d2 +(n -3)/3(d3)))

And this simplifies a little bit to ...

  Sn = 1 +(n -1)(4 +(n -2)(n +3)/2)

In simpler form, we have ...

  Sn = 1/2(n³ +n)

Then the two terms we're interested in are ...

  S7 = (1/2)(7³ +7) = 175

  S17 = (1/2)(17³ +17) = 2465

Each term Sₙ consists of the sum of a triangular number of terms, which are given by

[tex]T_n = \displaystyle \sum_{k=1}^n k = 1 + 2 + 3 + \cdots + n = \frac{n(n+1)}2[/tex]

The triangular numbers are given recursively for n ≥ 1 by

[tex]T_n = T_{n-1} + n[/tex]

starting with T₀ = 0.

For example,

• S₁ = 1 and

[tex]\displaystyle S_1 = \sum_{k=T_0+1}^{T_1} k = \sum_{k=1}^1 k = 1[/tex]

• S₂ = 2 + 3 and

[tex]\displaystyle S_2 = \sum_{k=T_1+1}^{T_2} k = \sum_{k=2}^3 k = 2 + 3[/tex]

• S₃ = 4 + 5 + 6 and

[tex]\displaystyle S_3 = \sum_{k=T_2+1}^{T_3} k = \sum_{k=4}^6 k = 4 + 5 + 6[/tex]

Then the n-th term of the sequence we're considering is

[tex]S_n = \displaystyle \sum_{k=T_{n-1}+1}^{T_n} k = \sum_{k=T_{n-1}+1}^{T_{n-1}+n} k[/tex]

Expanding this sum, we have

[tex]S_n = \left(T_{n-1}+1\right) + \left(T_{n-1}+2\right) + \left(T_{n-1}+3\right) + \cdots + \left(T_{n-1}+n\right)[/tex]

There are n terms on the right side, and hence n copies of [tex]T_{n-1}[/tex], and the rest of the terms make up the next triangular number [tex]T_n[/tex] :

[tex]S_n = nT_{n-1} + 1 + 2 + 3 + \cdots + n[/tex]

[tex]S_n = nT_{n-1} + \displaystyle \sum_{k=1}^n k[/tex]

[tex]S_n = nT_{n-1} + T_n[/tex]

We have a closed form for [tex]T_n[/tex], so we end up with

[tex]S_n = n \cdot \dfrac{(n-1)n}2 + \dfrac{n(n+1)}2 \implies \boxed{S_n=\dfrac{n^3+n}2}[/tex]

From here it's easy to find S₇ and S₁₇.

[tex]S_7 = \dfrac{7^3+7}2 \implies \boxed{S_7 = 175}[/tex]

[tex]S_{17} = \dfrac{17^3+17}2 \implies \boxed{S_{17} = 2465}[/tex]

[tex]slope = m = \cfrac{rise}{run} \implies \cfrac{ f(x_2) - f(x_1)}{ x_2 - x_1}\impliedby \begin{array}{llll} average~rate\\ of~change \end{array}\\\\[-0.35em] \rule{34em}{0.25pt}\\\\ f(x)= 2x^3+4\qquad \begin{cases} x_1=4\\ x_2=6 \end{cases}\implies \cfrac{f(6)-f(4)}{6-4} \\\\\\ \cfrac{[2(6)^3+4]~~ -~~[2(4)^3+4]}{2}\implies \cfrac{436~~ -~~132}{2}\implies \cfrac{304}{2}\implies 152[/tex]

Answer:

[tex] \frac{1}{2} \: \: \: \: \: \frac{1}{4 \: } \: \: \: \frac{1}{8} [/tex]

[tex] \frac{4}{8} \: \: \: \frac{2}{8} \: \: \: \frac{1}{8} [/tex]

She ate

[tex] \frac{7}{8} [/tex]

Answer:

The line shifted up 8 units

Step-by-step explanation:

Answer: c

Step-by-step explanation:

Answer: C

Step-by-step explanation:

[tex]▪▪▪▪▪▪▪▪▪▪▪▪▪  {\huge\mathfrak{Answer}}▪▪▪▪▪▪▪▪▪▪▪▪▪▪[/tex]

Area of quarter = 1/4 × Area of whole circle

that is ~

[tex] \sf \approx38.46 \: \: cm {}^{2} [/tex]

Answer:

Its 78,300

Step-by-step explanation:

m=-1 and c=8 for the line  y = 8 − x

The slope intercept form of a line is y=mx+b, where m is slope and b is the y intercept.

The slope of the line is the ratio of the rise to the run, or rise divided by the run. It describes the steepness of line in the coordinate plane.

The slope intercept form of a line is y=mx+b, where m is slope and b is the y intercept.

The slope of line passing through two points (x₁, y₁) and (x₂, y₂) is

m=y₂-y₁/x₂-x₁

The given equation is  y = 8 − x

This equation we can write in the form of slope intercept form

y=-x+8

y=(-1)x+8

Now compare the above equation with slope intercept form

m=-1 and c=8

Hence, m=-1 and c=8 for the line  y = 8 − x

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Answer:

answer below

Step-by-step explanation:

9(y = 1/9x + 5)

9y = x + 45

-x + 9y = 45

x - 9y = -45

Answer:

a) f(n) = 11 + f(n - 1)

Step-by-step explanation:

f(2) = 11 + 4 = 15

f(3) = 11 + 15 = 26

f(4) = 11 + 26 = 37

f(5) = 11 + 37 = 48

Answer:

A. 30% B. 45%

Step-by-step explanation:

A. 72,000/240,000 = x/100

(72,000)(100) = (240,000)x

7,200,000 = 240,000x

30 = x

B. 108,000/240,000 = x/100

10,800,000 = 240,000x

45 = x

The distance Jen is from the base of the lighthouse is 86.6 meters.

Trigonometric ratio is used to show the relationship between the sides of a and angles of a right angled triangle.

Let d represent the distance Jen is from the base of the lighthouse.

Using trigonometric ratios:

[tex]tan(30)=\frac{50}{d} \\\\d=\frac{50}{tan(30)} \\\\d=86.6\ m[/tex]

The distance Jen is from the base of the lighthouse is 86.6 meters.

Find out more on Trigonometric ratio at: https://brainly.com/question/10417664

Answer:

-10 degrees Celsius

Step-by-step explanation:

The more negative a temperature in degrees Celsius is, the colder it is.

Step-by-step explanation:

Relation

Hope it correct!!!

this may help you very much

Answer:

A. 4

Step-by-step explanation:

i guess it A. 4 i dunno

Four types

All types of python windows are

Answer:

x=13

Step-by-step explanation:

8x-20=4x+32

start by moving the terms,

8x-4x=32+20

combine

4x=52

divide each side by 4

x=13

Answer:

48 is 25% of 12

Step-by-step explanation:

Answer:

I think I've answered this question already.

Step-by-step explanation:

The vertices of the feasible region of the constraints is (0,2.5)

The constraints are given as:

x + 3y ≤ 6

4x + 6y ≥ 9

x ≥ 0,  y ≥ 0

Express the inequalities as equations

x + 3y = 6

4x + 6y = 9

Make x the subject in x + 3y = 6

x = 6 - 3y

Substitute x = 6 - 3y in 4x + 6y = 9

4(6 - 3y) + 6y = 9

Expand

24 - 12y + 6y = 9

Evaluate the like terms

-6y = -15

Divide by 6

y = 2.5

Substitute y = 2.5 in x = 6 - 3y

x = 6 - 3 * 2.5

Evaluate

x = -1.5

So, we have:

(x,y) = (-1.5, 2.5)

Recall that: x ≥ 0,  y ≥ 0

This means that the feasible region must have positive coordinates or zero

So, we set x = 0

(x,y) = (0, 2.5)

Hence, the vertices of the feasible region of the constraints is (0,2.5)

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Answer:

See answer below.

Step-by-step explanation:

This is true for all right triangle a² + b² = c²    were c = the largest number

9, 12, 15           A right triangle

21, 28, 35       A right triangle

9, 13, 16          Not a right triangle

10, 11, 15          Not a right triangle

Step-by-step explanation:

An acute triangle is a triangle whose angles are all acute (i.e. less than 90°). In the acute triangle shown below, ∠a, ∠b and ∠c are all acute angles. Example 1: A triangle has angles 46°, 63° and 71°.

Answer:

21x-28

Step-by-step explanation:

the distributive property states that a(bx+c) is equal to abx+ac. in this expression, a is 7, b is 3, and c is negative 4. ab is 7*3, which is 21, so abx is 21x. ac is 7*-4, which is -28. combining these two results in 21x-28.

Answer:

21x-28

Step-by-step explanation:

distribute the 7 to the 3x & the -4

you get 21x-28

Answer:

1) -15/4

2) -15/2

Step-by-step explanation:

1) Let u=4t. Then the limits become u=4(0)=0 and u=4(4)=16. Also du=4 dt upon differentiating the equation.

So the integral can be written as

Integral( 1/4 f(u) , u=0 to u=16)

We are given Integral( f(u) , u=0 to u=16) is -15. So a fourth of that is our answer for the first question.

2) Let u=t^2. Then the limits become u=(0)^2=0 and u=(4)^2=16. Also upon differentiating we obtain equation du =2 t dt.

So the integral becomes

Integral( 1/2 f(u) , u=0 to u=16).

We are given Integral( f(u) , u=0 to u=16) is -15. So a half of that is our answer for the second question.

Answer:

it is d

Step-by-step explanation:

Answer:

y=4x-3

Step-by-step explanation:

Answer:

DO i care... no ask your dam teacher won der why u aint pass

Step-by-step explanation:

Answer: 4.5

Step-by-step explanation:

30% is equal to 30/100, which is 0.3

If you times 0.3 by 15, you will get 30% of 15

Therefore the answer would be 0.3 x 15 = 4.5