What’s the formula for the series -5,10,-20,40

Answers

Answer 1

Answer:

Stare at it long enough. You will notice that with each step you double the value, and change sign. It makes it a geometric sequence of ratio -2. At this point you have two ways of writing down:

Option 1: Ricorsively, the first term is -5, then the next term is -2 times the previous one:

[tex]\left \{ {{a_0=-5} \atop {a_{n+1}=-2a_n}} \right.[/tex]

Option 2: In closed form, remembering that the n-th term in a geometric sequence is the starting term times the n-th power of the ratio:

[tex]a_n=-5 (-2)^n[/tex]

Either work, depending on what you need to use it for.


Related Questions

Write each verbal expression as an algebraic expression.

The product of a number, b, and nine =




​A number, x, raised to the fifth power =


​Twelve divided by the product of number, y, and three =


​Seven added to the difference of one and a number, k =

Answers

1. 9b
2.x^5
3.(3y)/12
4.(1-k)+7

What is the equation for the line in slope-intercept form?
Enter your answer in the box.

Answers

Answer:

y= -4/2x+ -4

Step-by-step explanation:

looked at the graph

Choose correct way to write 7 cents using the dollar symbol.


$.07




$ 7 ¢






$.07 ¢




$.7

Answers

$.07. You do not write $.7 because that would mean 70 cents and should be written with a 0 at the end anyways. You do not write any dollar amount with a cents sign at the end, because the dollar sign replaces it. You write $.07 because 7 cents means 7/100 (7 one hundredths) so the seven must be written in the hundredths spot. Remember, the hundredth spot is the second number after a decimal.

Step-by-step explanation:

$.07

$.7

The answer was first one.

Does the graph represent a function?

Answers

Answer:

yes, it's a function

Step-by-step explanation:

downward facing parabola

I need help
With this one question

Answers

Answer:

$88

Step-by-step explanation:

442.70 rounded to the nearest 10 dollars is 440.

20%= .2.

440 times .2 =

88

Write the following as a mathematical sentence. Use the letter n as your variable.

​Seven less than a number is two.

Answers

Answer:

n-7=2

Step-by-step explanation:

We can start with one side, which is: seven less than a number

Since the number is n, seven less than it is n-7

The other side 2, as we can see after the word is

The equation, therefore, is

n-7=2

6 wholes and 1/3 converted into decimal?

Answers

Answer:

6 is a whole number.

[tex]\frac{1}{3}[/tex] is approximately equal to 0.333, but this is a repeating decimal.

Find radiuses of circles, if OO1=20cm and 3AK=2BK

Answers

Answer:

radius of smaller circle on the left =  8 centimetersradius of larger circle on the right =  12 centimeters

=============================================================

Explanation:

The letter O looks very similar to the number zero, so I'm going to use other letters to avoid confusion. For the smaller circle on the left, it'll have center P. The circle on the right will have center Q. See the diagram below.

Based on that, we can say that PQ = 20 cm.

Let x = length of PK

PK + KQ = PQ

KQ = PQ - PK

KQ = 20 - x

We'll keep this in mind for later. I'll refer to this as "Fact 1" when it does come up later.

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

We're given this equation

3AK=2BK

Let's get the numbers to one side and the letters to the other side like so:

3AK=2BK

3AK/BK = 2

AK/BK = 2/3

We'll use this later as well.  I'll refer to this as "Fact 2" when it does come up later.

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

Next, draw a segment from P to A to form triangle PAK (also shown in the diagram below). Do the same for points Q and B to form triangle QBK.

The segments PA and PK are radii of the smaller circle, so PA = PK which leads to triangle PAK being isosceles. Triangle QBK is also isosceles for similar reasoning.

The angles AKP and QKB are vertical angles, so they are congruent.

The facts mentioned so far boil down to the two triangles being similar triangles (use the angle angle method to prove).

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

Now that we know the triangles are similar, we can use a proportion to solve for x.

PK/KQ = AK/KB

PK/KQ = 2/3  .... use fact 2

x/(20-x) = 2/3 .... use fact 1

3x = 2(20-x) .... cross multiply

3x = 40 - 2x

3x+2x = 40

5x = 40

x = 40/5

x = 8

So,

PK = x = 8KQ = 20-x = 20-8 = 12

The radius of the smaller circle on the left is 8 cm.

The radius of the larger circle on the right is 12 cm.

What are the first five terms of the arithmetic progression with the first term 8 and common difference 7 , then find the 17th?.

Answers

Step-by-step explanation:

a1 = 8

a2 = 8 + 7 = 15

a3 = 15 + 7 = 22

a4 = 22 + 7 = 29

a5 = 29 + 7 = 36

an = an-1 + 7 = a1 + 7×(n-1)

a17 = 8 + 7×16 = 8 + 112 = 120

write 164/100 as a mixed number in simplest form.

Answers

Answer:

1 16/25

Step-by-step explanation:

I just recently learned this kind of stuff!

Answer:

1 16/25

Step-by-step explanation:

164-100=64

Common factors of 64 and 100:

1, 2, 4

Greatest common factor: 4

64/4=16

100/4=25

16/25

1 16/25

write an expression that shows 9 less than the product of 11 and 3.5

Answers

try this for answer (11×3.5)-9=x

NEED NOW PLEASE..........

Answers

Answer:

The answer is 6 feet below the surface of the water.

Step-by-step explanation:

So the fish started out as 12m below the surface then went 3m down. If you add 12m and 3m you'll 15m, then minus with a 9m to came up with 6m. But the fish is still below surface, which gives you the answer of " 6 feet below the surface"

Hopes this helped you :)

45% of the people in the stadium are men, 23% of them are woman and the rest are children. What fraction of the people are children?​

Answers

Answer:

8/25 of the people in the stadium are children.

Step-by-step explanation:

45 + 23 = 68

100 - 68 = 32%

32/100 simplified is 8/25

Graph the solution to the following system of inequalities.
-7x + 5y < -10
5x + 4y > 8
Then give the coordinates of one point in the solution set.

Answers

Graph attached

Solution is (1.6,0)

Can someone pls help me!! And if u can explain how u do it I will very thankful for that..

Answers

Answer:

For the first question is 8y, and the second question would be 80

Step-by-step explanation:

The perimeter of a shape is calculated by adding it's sides together, and 2y+2y+2y+2y=8y. If y=10, we can substitute y for 10 in which 8*10 is 80.

Find the x-intercepts of the parabola y=−x2+x+12.

Answers

Answer:

Your x-intercepts are -(3, 0) and (4, 0).

Step-by-step explanation:

Vertex:
(1/2 , 49/4)

y-intercept: 12

x-intercepts: 4 and (−3)

a carpet cleaning service charges a one-time service fee of $100 with an additional $15 per hour for their business. write a linear equation that represents the total cost (y) for the hours work (x)

Answers

Answer:

The answer is y= 100 +15x

Step-by-step explanation:

You start with a service fee of $100

$15 per hour

x because the amount of hours can vary

y which is the total cost

y= 100+ 15x

Which value of y makes the equation y+4.2=21 true?
I NEED THE ANSWER ASAP I ONLY HAVE 20 MINS TO COMPLETE


A. y = 16.8
B.y=17.2
C.y=17.8
D=25.2

Answers

Answer:

A: 16.8

Step-by-step explanation:

4.2 and 16.8 both have decimal place values. If you line up the decimals when you add them, then you get 21.

1. Which of the following is the remainder when the polynomial x^2-5x+3 is divided by (x -8)?
(1) 107
(3) 3
(2) 27
(4) 9

Answers

Answer:

27

Step-by-step explanation:

Use synthetic division:

8 | 1 -5 3

   __8_24

    1  3 | 27

Therefore, (x²-5x+3)/(x-8) = x+3 R27

help please use picture

Answers

Answer:

y= -1x+4

Step-by-step explanation:

-1/1 is simplified to -1

Help!!!!!!please help i will fail

Answers

Answer:

WHAT is to solve their is notting

Step-by-step explanation:

MARKING AS BRAINLIEST!! Starr if given functions are inverse)!

Answers

Answer: They are inverses of each other

==========================================================

Explanation:

We'll need to compute h(f(x)) and f(h(x)) to see if we get x each time.

[tex]h(x) = 9x-4\\\\h(f(x)) = 9(f(x))-4\\\\h(f(x)) = 9\left(\frac{x+4}{9}\right)-4\\\\h(f(x)) = x+4-4\\\\h(f(x)) = x\\\\[/tex]

and,

[tex]f(x) = \frac{x+4}{9}\\\\f(h(x)) = \frac{h(x)+4}{9}\\\\f(h(x)) = \frac{9x-4+4}{9}\\\\f(h(x)) = \frac{9x}{9}\\\\f(h(x)) = x\\\\[/tex]

Both composite functions lead to x each time.

The equations h(f(x)) = x and f(h(x)) = x being true means each function is the inverse of the other.

Ok done. Thank to me:>

There is a cookie jar in Julio's kitchen filled with 7 cookies. His mother bakes some more cookies. Now there are 14 cookies. How many cookies did Julio's mother bake.

Answers

The Answer is 7 cookies because she had 7 cookies filled in the jar and after making 7 more it becomes 14 so
Also 7+7=14

Name.
Solve using
Substitution
L
y = 3x + 2
6x - 2y = 8

Answers

Answer:

No solution

Step-by-step explanation:

There is no solution to the system of equations y=3x+2 and 6x-2y=8, meaning that they are parallel to each other on a graph, with no points ever intersecting on each other's lines.

What is the equation for the line in slope-intercept form? 20 18+ Enter your answer in the box. 16+ 14+ 112+ NO+ 6 4 2 - 20-18 -16-14-12-10 -9 -6 -4 4 6 8 -20 -27 10 12 14 16 18 20 -4- -B -8 -10 -12+ -14H -16+ -18+ -20+​

Answers

The slope of the line represents that the remainder of the goal decrease by 8 for each card sold.

A linear equation is in the form:

y = mx + b

where y, x are variables, m is the slope of the line and b is the y intercept.

The line passes through the point (1, 8) and (2, 16), hence:

[tex]y-y_1=\frac{y_2-y_1}{x_2-x_1} (x-x_1)\\\\y-8=\frac{16-8}{2-1}(x-1)\\\\y=8x[/tex]

The equation of the line is given by y =8x

Find out more about linear equation at: https://brainly.com/question/14323743

Find out more on linear equation at: https://brainly.com/question/14323743

Given f(x)=x2-1/x+4 find f(-3)

Answers

f(-3)=(-3)2 - 1 / -3 + 4
f(-3)= -6 -1 / -3 + 4
f(-3)= -7/1
f(-3)=-7

IF the domain is {0, 2, -6}, what is the range of y=-2x+3?

Answers

Answer:

Range is {3,-1, 15}

Step-by-step explanation:

Answer:

{3, -1, 15} is the range.

Step-by-step explanation:

please help i only have a few minutes!! what are the measurements for 1 and 2?

Answers

Answer:

8 tablespoons1/2 cup4 ounces10 tablespoons plus 2 teaspoons2/3 cup5.2 ounces12 tablespoons3/4 cup6 ounces16 tablespoons1 cup8 ounces

How long it would it take to spread a rumor in a town of 90,000 people if each person who heard the rumor told it to 3 new people every 15 minutes?

Answers

Answer:

it would take 30k minutes, equivalent to 500 hours/almost 21 days/almost 3 weeks

Step-by-step explanation:

What are the roots of the equation x^2+18x+90=0x
2
+18x+90=0 in simplest a+bia+bi form?

Answers

[tex]x^2 +18x +90 = 0\\\\\text{Apply quadratic formula,}~~ x = \dfrac{-b \pm \sqrt{b^2 -4ac}}{2a} \\\\\text{In this case, a = 1 , b = 18 and c = 90.}\\\\\implies x = \dfrac{-18 \pm \sqrt{18^2 - 4 \cdot 1 \cdot 90}}{2(1)}\\\\\implies x = \dfrac{-18 \pm \sqrt{-36}}2\\\\\implies x = \dfrac{-18 \pm 6i}2\\\\\implies x= -\dfrac{18}2 \pm \dfrac{6i}2\\\\\implies x= -9 \pm 3i[/tex]

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