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SSSSS [86.1K]
3 years ago
13

Find the sum of the first 9 terms of the geometric series: 3 + 21 + 147 + …

Mathematics
1 answer:
grin007 [14]3 years ago
8 0

Answer:

  20,176,803

Step-by-step explanation:

This geometric series has a first term of 3 and a common ratio of 21/3 = 7. The formula for the sum of n terms of a series with first term a1 and common ratio r is ...

 Sn = a1·(r^n -1)/(r -1)

For a1=3, n=9, and r=7, the sum is ...

  S9 = 3·(7^9 -1)/(7 -1) = 3·40353606/6 = 20,176,803

The sum of the first 9 terms is 20,176,803.

_____

The first 9 terms are ...

  3 +21 +147 +1029 +7203 +

  50,421 +352,947 +2,470,629 +17,294,403

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A student concludes that for all values of x,x^2+x+1 produces a prime number. Which value of x serves as counterexample to prove
Dafna11 [192]

Answer:

j

Step-by-step explanation:

Substitute the given values into x² + x + 1 and check if result is prime

x = - 4

(- 4)² - 4 + 1 = 16 - 4 + 1 = 13 ← prime

(- 2)² - 2 + 1 = 4 - 2 + 1 = 3 ← prime

(- 3)² - 3 + 1 = 9 - 3 + 1 = 7 ← prime

4² + 4 + 1 = 16 + 4 + 1 = 21 ← not prime

x = 4 serves as a counterexample to disprove this conclusion

5 0
2 years ago
Which of the following functions has a period of 8 π ?
KengaRu [80]
<h3>Answer: Choice B</h3>

Explanation:

The general template of a sine function is

y = Asin(B(x-C))+D

The value of B is the only thing that determines the period T. We ignore every other term.

It turns out that T = 2pi/B which can be solved to B = 2pi/T

Plug in the given period of T = 8pi and compute to get

B = 2pi/T

B = (2pi)/(8pi)

B = 2/8

B = 1/4

This means that the term out front of the x is 1/4 and the equation must be y = \sin\left(\frac{1}{4}x\right) which matches with answer choice B.

4 0
3 years ago
Write the equation of the line represented by the following table
s344n2d4d5 [400]

Answer:

y = 100x + 400

Step-by-step explanation:

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

Calculate m using the slope formula

m = (y₂ - y₁ ) / (x₂ - x₁ )

with (x₁, y₁ ) = (0, 400) and (x₂, y₂ ) = (1, 500) ← 2 points from the table

m = \frac{500-400}{1-0} = 100

note the line crosses the y- axis at (0, 400) ⇒ c = 400

y = 100x + 400 ← equation of line

4 0
3 years ago
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galina1969 [7]

Answer:22

Step-by-step explanation: the smallest the other two can be is 1 so you have to multiply 8 with 3, that equals 24, then you have to subtract 2         (1+1) and that gives you 22.

4 0
3 years ago
50 POINTS !!<br><br><br> PLEASE HELP !! ILL GIVE BRAINLIEST TO THE RIGHT ANSWERS.
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Answer:

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Step-by-step explanation:

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3 years ago
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