the sum of the first ten terms of a linear sequence is -60 and the sum of the first fifteen terms is -165. Find the 18th term of the sequence​

Answers

Answer 1

Answer:

         a₁₈ = - 31

Step-by-step explanation:

[tex]S_{10}=\dfrac{2a_1+d(10-1)}{2}\cdot 10\\\\\dfrac{2a_1+9d}{2}\cdot 10=-60\\\\\dfrac{2a_1+9d}{2}=-6\\\\2a_1+9d=-12\\\\2a_1=-12-9d\\\\\\S_{15}=\dfrac{2a_1+d(15-1)}{2}\cdot 15\\\\\dfrac{2a_1+14d}{2}\cdot 15=-165\\\\\dfrac{2a_1+14d}{2}=-11\\\\2a_1+14d=-22\\\\-12-9d+14d=-22\\\\ 5d=-10 \\\\ d=-2\\\\\\2a_1=-12-9(-2)=-12+18=6\\\\a_1=3\\\\\\ a_{18}=a_1+17d=3+17(-2)=3-34=-31[/tex]


Related Questions

calculate the mean deviation for the number 75 85 96 100 121 125

Answers

Answer:

i got 15.1

Step-by-step explanation:

the quality rating of 8 movies showing at a movie theater near you is 5.6, 7.9, 7.0, 5.9, 7.8, 6.2, 6.4, and 5.2. What do the ninth movies need to be for the theater to average a movie rating of 6.4?

Answers

Answer:

5.6

Step-by-step explanation:

Given :

Quality rating for 8 movies :

5.6, 7.9, 7.0, 5.9, 7.8, 6.2, 6.4, 5.2

Let rating for the 9th movie = x

Average quality rating olfor the 9 movies = 6.4

To find x :

Sum of all ratings / number of ratings = 6.4

(5.6 + 7.9 + 7.0 + 5.9 + 7.8 + 6.2 + 6.4 + 5.2 + x) / 9 = 6.4

(52 + x) / 9 = 6.4

52 + x = 57.6

x = 57.6 - 52

x = 5.6

13. In the right triangle depicted below, what is the cosine of angle B?

Answers

Answer:

number c

Step-by-step explanation:

.............. just for filling 20 characters

the cosine of angle B

C. 0.767

How do you find the cosine of a triangle?

the cosine of an angle in a right triangle equals the adjacent side divided by the hypotenuse: Also, cos A = sin B = b/c.

The cosine formula to find the side of the triangle is given by: c = √[a2 + b2 – 2ab cos C] Where a,b and c are the sides of the triangle.

Pythagoras Theorem is a generalization of the Law of Cosine.

The law of cosine can be applied in any triangle.

Learn more about the cosine of a triangle here

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A park charges $13 for one round of miniature golf and a reduced fee for each additional round played. If Tom paid $43 for 6 rounds of miniature golf, what is the reduced fee for each additional round played?

Answers

Answer:

Reduced fee for each additional round will be $5.

Step-by-step explanation:

Let the reduced fee for each additional round played = $x

Charges for one round = $13

If Tom played for 6 rounds, total charges for the 6 rounds = 13 + 6x

Since, Tom paid $43 for 6 rounds,

13 + 6x = 43

6x = 43 - 13

6x = 30

x = 5

Therefore, reduced fee for each round will be $5.

Half of the sum of 3x and 4

Answers

Answer:

1.5x + 2

Step-by-step explanation:

(3x + 4)/2 = 1.5x + 2

given parallelogram ABCD with A(-3,0), B(-2,3), C(3,2) and D(2,-1) find the coordinates of the diagonals AC and BD

Answers

Plot graph and count for A.

A (-1,10)

If 23,600,000 is written as 2.36 x 10" what is the value of n?

Answers

Step-by-step explanation:

there are 7 decimal places from between 2 and 3 to the very end. so the answer is 7

Answer: 2.36x^10

Step-by-step explanation:

What is the numerical probability of selecting a jury with 10 men and 2 women?

out of 29 men and 26 women

Answers

Answer:

Let E denote the event of choosing a jury with 10 men and 2 women.

The sample space for selecting 12 members from the pool contains 55C12 elements.

The number of ways of selecting 10 men and 2 women is 26C10  29C2.

The probability of event E =  

The probability of selecting a jury with 10 men and 2 women is 0.005 (0.5%).

Step-by-step explanation:

see the image :

Answer:

The probability of selecting a jury with 10 men and 2 women out of out of 29 men and 26 women  is 0.005 (0.5%)

Step-by-step explanation:

Let P(E) denote the probability of choosing a jury with 10 men and 2 women out of 29 men and 26 women.

The sample space for selecting 12 members from the total no of member will be 55c12

The number of ways of selecting 10 men and 2 women is 26c10  29c2.

The probability of event E =  [tex]$=P(E)=\frac{{ }_{20} C_{10} \times{ }_{20} C_{2}}{-C_{12}}$[/tex]

                                                [tex]$=\frac{5,311,735 \times 406}{438,729,741,450}$[/tex] [tex]$=0.005$.[/tex]

The probability of selecting a jury with 10 men and 2 women is 0.005 (0.5%).

Click here to know more about the probability .

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If y = 2,300 (3x), what is y if x = 3?

No files or links. Just answers.

Answers

Answer:

20700

Step-by-step explanation:

3 times 3 times 2300 = 20700

Seraphina is driving two hours to visit her family. For the first hour, she traveled at a speed of 60 miles per hour. Then, in the second hour, she traveled at a speed of 65 miles per hour. What is the percentage increase of Seraphina's speed? If necessary, round to the nearest tenth of a percent

Answers

Answer:

There was a %5 increase

Step-by-step explanation:

You just have to substract 65-60 and you get 5

PLEASE HELP 10 POINTS PLEASE

Answers

Answer:

80 Degrees

Step-by-step explanation:

just flip and overlap the figure (in your mind)

-3 x -3 - 6 +2 =

Show our work

Someone help I will give u brain list + 11 points

Answers

-3 x -3 = 9
9-6= 3
3+2 = 5

the answer is 5

What is the answer to 6 ^-2?

Answers

Answer: 0.02777777777

Step-by-step explanation:

What is the value of v? Help, please

Answers

Answer:

v = 87

Step-by-step explanation:

the angle v+39 lies on a straight line. so substract v+39 from 180 to get the interior angle for that side.

afterwards, knowing that the sum of interior angles of a triangle = 180, form an equation with all the angles and solve for v

Find the slope between the two points, 1. (1. 7), (2, 4) 2. (-3, 5), (6,2)​

Answers

The first one is -3 , The second one is -1/3

Geometry help please! Thank you

Answers

Answer:

ZWXY

Step-by-step explanation:

The other shape is the same but you want to name it the same way that they named the first one

PLEASE HELP!!!!!! 15POINTS!!!!!!!!! REAL ANSWERS ONLY!!!!!! NO LINKS!!!!!!!​

Answers

Answer:

Solution given:

radius [r]=40ft

length of arc=70/360×2πr=70/360×2×π×40

=48.86=49ft is your answer

Answer:

49ft is the answer. hope it helps

Paula is making posters for the school election. The table shows the number of posters, , she can make in m minutes. which equation represents the relationship between the number of posters she can make and the time and minutes it takes her to make the posters. please help​

Answers

Answer:

KitKat

Step-by-step explanationKitKat

pleaseee what is ittt

Answers

Answer:

positive slope is shown by the graph

Help!!!!!!!!!!plz!!!!!!!!!!!!

Answers

Answer:

16

Step-by-step explanation:

By intersecting secants theorem:

[tex]9(2x - 17 + 9) = 8(8 + 10) \\ \\ 9(2x - 8) = 8 \times 18 \\ \\ 2x - 8 = \frac{144}{9} \\ \\ 2x - 8 = 16 \\ \\ 2x = 16 + 8 \\ \\ 2x = 24 \\ \\ x = \frac{24}{2} \\ \\ x = 12[/tex]

CE = 9 + (2x - 17)

CE = 9 + (2*12 - 17)

CE = 9 + (24 - 17)

CE = 33 - 17

CE =16

If the measure of angle 2 is 100 degrees. What is the measure of angle 8? Why?

Answers

Answer:

5

Step-by-step explanation:

thanks for the points


Which is the equation of the line that has a slope of -3 and includes the point (2, 4)?

Answers

Answer:

y= -3x + 10

Step-by-step explanation:

we can answer this question thanks to this formula:

y-y1 = m(x-x1) where y1 and x1 indicate the coordinates of the given point and m indicates the slope

y-4 = -3(x-2)

y = -3x+6+4

y= -3x + 10

Hewwo!
[tex] \underline{ \underline{ \bf{Question}}} : [/tex] In a circle of radius 5 cm , AB and CD are two parallel chords of length 8 cm and 6 cm respectively. Calculate the distance between the chords , if they are :
i. on the same side of the centre
ii. on the opposite side of the centre
*Show your workings!

Answers

Answer:

AB=8cm⇒AE=4cmCD=6m⇒CF=3cmIn△AEDAE=4cm,AO=5cmOE=(AO)2−(AE)2=52−42=3cmIn△OFCCF=3cm,CO=5cmOF=OC2−CF2=52−32=4cm

∴ Distance between the chords=4cm−3cm=1cm

Answer:

I) 1 cm

II) 7 cm

Step-by-step explanation:

We are given a circle with a radius of 5 cm. AB and CD are two parallel chords of length 8cm and 6cm respectively. And we want to calculate the length of the chords if they are:

I) On the same side of the center.

Please refer to the first figure.

In it, O is the center, AB measures 8 and CD measures 6.

To find the distance between the two chords, we essentially need to find KJ, which is OJ - OK.

We will construct a segment from O to K and from K to J. This is perpendicular to the chords. Therefore, by the Perpendicular Bisector Theorem, it also bisects the chords.

ΔAOK is a right triangle. Therefore:

[tex]AO^2=OK^2+KA^2[/tex]

AO is simply the radius.

KA is half the length of AB since OK perpendicularly bisects the chord.

Therefore:

[tex](5)^2=OK^2+(4)^2[/tex]

So:

[tex]25=OK^2+16\Rightarrow OK^2=9\Rightarrow OK=3[/tex]

Likewise, ΔCOJ is also a right triangle. Therefore:

[tex]CO^2=OJ^2+JC^2[/tex]

CO is the radius, and JC will be half the length of CD. Thus:

[tex](5)^2=OJ^2+(3)^2\Rightarrow OJ^2=16\Rightarrow OJ=4[/tex]

Therefore, the distance KJ between the two chords are:

[tex]KJ= OJ-OK=4-3=1\text{ cm}[/tex]

II) On opposite sides of the center.

Please refer to the second figure.

Again, O is the center, AB measures 8, and CD measures 6.

Likewise, segments OK and OJ are perpendicular bisectors of AB and CD, respectively.

And to find the distance, we essentially need to find JK or OJ + OK.

ΔKOB is a right triangle. Thus:

[tex]OB^2=OK^2+KB^2[/tex]

OB is the radius, and KB is half of AB:

[tex](5)^2=OK^2+(4)^2\Rightarrow OK=3[/tex]

ΔJOD is also a right triangle. Thus:

[tex]OD^2=OJ^2+JD^2[/tex]

OD is the radius and JD is half of CD:

[tex](5)^2=OJ^2+(3)^2\Rightarrow OJ=4[/tex]

Therefore, the distance between the two chords are:

[tex]JK=OJ+OK=4+3=7\text{ cm}[/tex]

Can someone answer these 3 plz like I need these so bad rn. I would really appreciate it if someone who knows it can answer and help me out! Thank you

Answers

Answer:

for the first photo the answer is 5x + 6(-x + 4) = 13

Step-by-step explanation:

if y equals to -x +4

then replace the y in this equation: 5x + 6y = 13  with this ( -x +4 ) its simple.

I cannot answer the other 2 photos at the moment but ill see if I can whenever else I have time.

1. What kind of polyhedron can be assembled from this net?
2. Find the surface area (in square units) of the polyhedron. Show your reasoning.

Answers

Answer:

Honestly it looks like a rectangular prism.

Step-by-step explanation:

Picture that you're folding it. the dark lines are the crevaces that you fold on.

Twenty years ago, Mr. Davis purchased his home for $160,000. Since then, the value of
the home has increased about 5% per year. How much is the home worth today?

Answers

Answer:

The home is worth $424,528 today

Step-by-step explanation:

To get the worth of the home today, we are going to use the exponential formula

We have this as follows;

A = P(1 + r)^t

where A is the value of the house after some time t

P is the initial value the home was worth which is $160,000

r is the rate of increase in the price of the home which is 5% = 5/100 = 0.05

t is the number of years which is 20

substituting these values;

A = 160,000(1 + 0.05)^20

A = $424,528

A triangular prism has a height of 9 meters and a triangular base with the following dimensions.

What is the volume of the prism?

- 420 m^3

- 288 m^3

- 324 m^3

- 432 m^3

Answers

Answer:

V = 432 m³

Step-by-step explanation:

The volume (V) of a prism is calculated as

V = Ah ( A is the area of the base and h the height )

A = [tex]\frac{1}{2}[/tex] bh ( area of triangular base, with b the base, h the perpendicular height)

Here b = 16 and h = 6 , then

A = [tex]\frac{1}{2}[/tex] × 16 × 6 = 8 × 6 = 48 m²

Then

V = 48 × 9 = 432 m³

what is the solution to the equation?
x=3
x=1
x=-1
x=-3

Answers

Answer:

x= - 3

Step-by-step explanation:

2x - 3= 4x + 3

2x = - 6

x = - 3

Convert the following angle from degrees to radians. Express your answer in simplest
form.
360°

Answers

Answer:

360° 2π rad 6.283185 rad

Plzz help will mark brainliest don't do it for the points plzz!!!!

Answers

Answer:

Your answer will be A. positive correlation

Step-by-step explanation:

hope this helps :)

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