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ANEK [815]
3 years ago
8

What is the sum of the geometric series in which a1 = −5, r = 3, and an = −405?

Mathematics
1 answer:
marysya [2.9K]3 years ago
3 0
An = a1 * r^(n-1)

-405 = -5*3^(n-1)

3^(n-1) = 81

3^4 = 81  so n-1 = 3  and n =  4

Sn  = S4  =  -5 (1 - 3^4)   / ( 1 - 3)   =  400 / -2 = -200 Answer
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You made two deposits to your bank account this month. One deposit was $24.61, and the second deposit was $16.49. Your balance a
Rina8888 [55]

The <em><u>correct answer</u></em> is:

$72.31 – $24.61 – $16.49; $31.21

Explanation:

We know we end the month with $72.31.

We made two deposits during the month and no other activity.  This means if we take the amounts of the deposits away from the total at the end of the month, we can find how much we had at the beginning of the month:

72.31-24.61-16.49 = 31.21

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division problem

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3 years ago
One fourth of the 120 students took wood shop. How many students did not take wood shop?
yawa3891 [41]

Answer:

90 students.

Step-by-step explanation:

Given 1/4 of the 120 students took woodshop, just take the 3/4 that didn't take it:

\frac{3}{4}(120)

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3 years ago
Which of the following is being constructed in the image.
Sliva [168]

Answer:

  3. a line perpendicular to a given line through a point not on the line

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The point not on the line suggests that choices 1 and 3 are possibilities. The fact that the dotted line is not parallel (and is perpendicular) to the solid line suggests that choice 3 is applicable and choice 1 is not.

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Please work out and explain​
Mekhanik [1.2K]

Answer:

a = 22

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Step-by-step explanation:

The sum is the same in each row, column, and diagonal.

One of the diagonals is already complete.  The sum is:

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So the first row adds up to 75:

a + 37 + 16 = 75

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We can check our answer by finding the sum of each column and the other diagonal.

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