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3 years ago

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:

Step-by-step explanation:

<h3>Given GP with:</h3>

a1 = 10
r = -2

<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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S = 2r + 3 × solve for x

Assoli18 [71]

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4 years ago

PLEASE HELP ASAP!!!

Dimas [21]

Step-by-step explanation:

5x^2+2x=1

5x^2+2x-1=0

x=-b+/-√b^2-4ac÷2a

x=-2+/-√-2^2-(4×5×-1)÷2×5

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3 years ago

Read 2 more answers

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Sliva [168]

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8 0

3 years ago

(20+80 divided by 2x8) divided [(54 divided by 9+14)divided by 4]

lesya692 [45]

Answer:

Step-by-step explanation:

Let's write out the equation:

8(20+80/2)/[(54/9+14)/4]

For the first part we get 8(100/2)

Then 50x8

Then 400

For the second part we have (6+14)/4 as we divide 54 by 9. PEMDAS

Then 20/4

Then 5

So our final answer is 400/5 which is 80.

Hope this helps!

7 0

3 years ago

Alvin is 11 years younger than Elga. The sum of their ages is 43. What is elgas age

Neporo4naja [7]

Answer:

Step-by-step explanation:

Lets assume x is Elgas' age

And y is Alvins age

we know that alvin is 11 years younger than Elga which means,

x=y+11

and the sum of their age is 43

x+y=43

solve it and you get 16

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3 years ago