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Sholpan [36]
3 years ago
14

What is the sum of the first seven terms of the geometric series where a1 = 10 and r = −2?

Mathematics
1 answer:
lbvjy [14]3 years ago
5 0

Answer:

  • 430

Step-by-step explanation:

<h3>Given GP with:</h3>
  • a1 = 10
  • r = -2
<h3>To find</h3>
  • S7
<h3>Solution</h3>

<u>Formula of sum:</u>

  • Sn = a1(r^n - 1)/(r - 1)

<u>Substitute values:</u>

  • S7 = 10((-2)^7 - 1)/(-2 - 1) = 10(- 128 - 1)/(-3) = 10*129/3 = 430
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Winne is currently considering two plans for paying for piano lessons.
SVEN [57.7K]

Answer:

Plan B

Step-by-step explanation:'

First u have to divide each one to see how much each piano lesson costs.

Plan A- 31.50/6=5.25

Plan B- 20.60/4=5.15

So since Plan B is less then Plan B would be the answer.

(Brainliest Plz)

6 0
3 years ago
There are two question please help.
natima [27]
7 , it’s x = 12 1/3, or in decimal form, 12.33. And at 8, it’s x = -6/11, or in decimal form, -0.54
5 0
3 years ago
Between the time Iko woke up and lunchtime, the temperature rose by 11°. Then by the time he went to bed, the temperature droppe
Tanzania [10]

Answer:             -3 degrees

Step-by-step explanation:

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The temperature rose by 11 degrees so it is now at 11+x.

Then the temperature fell by 14 degrees so you subtract. 11+x-14

11-14= -3 so you subtract 3 degrees from the original temperature and there fore the relative temperature is -3

I hope this helps!!!

4 0
3 years ago
The function f(x) = 1.50x + 12.50 relates how much Kelsey pays for digital service, f(x), to the number of movies, x, she stream
Kobotan [32]
Hi there! f(18) makes the value of x 18 and x is the number of movies watched in 1 month. Therefore, A and C are eliminated because we’re talking 18 movies, not 18 months. B is also out, because Kelsey would pay more than $27 a month for the service, especially with the service fee. 18 * 1.50 is 27 and 27 + 12.50 is 39.50. Kelsey spends $39.50 a month watching 18 movies per month. The answer is D.
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3 years ago
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hram777 [196]
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First solve for the slope, m.

m = (162.5 - 45) / (570 - 100)
m = 117.5 / 470
m = 0.25

Not only is "m" the slope but it is the rate (dollars per minute) in the question. So it's 25 cents per minute to use the phone.
After imputing "m"  the linear equation looks like this:
y = 0.25x + b

Use either point as (x,y) to solve for the y-intercept "b". I'll use (100,45)

45 = 0.25(100) + b
45 = 25 + b
45 - 25 = b
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Not only is "b" the y-intercept but it is also always the flat fee added on to linearly increasing cost questions like this.

Final equation is:
y = 0.25x + 20

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y = 0.25(939) + 20
y = 234.75 + 20
y = 254.75

8 0
4 years ago
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