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trapecia [35]
3 years ago
8

In an arithmetic series, what is the sum of the first 22 terms if the first term is 12 and the common difference is 3?

Mathematics
1 answer:
Vilka [71]3 years ago
4 0

Answer:

561

Step-by-step explanation:

an = dn - (a-d)

The difference is 3.

The first term is 12.

an = 3n - (12-3)

an = 3n - 9

Put n as 1, 2, 3, 4, 5 ....22.

3(1) - 9 = -6

3(2) - 9 = -3

3(3) - 9 = 0

3(4) - 9 = 3

3(5) - 9 = 6

...

3(22) - 9 = 57

Add the first 22 terms.

-6+-3+0+3+6+9+12+15+18+21+24+27+30+33+36+39+42+45+48+51+54+57

= 561

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The answer is 8km.

1:100,000 = 1.6 miles = 1 kilometer x 8 = 8 km
4 0
3 years ago
James has a certain amount of money. If he buys $3$ pens and $2$ pencils, he will have $\$2$ left over. If he buys $2$ pens and
labwork [276]

The cost of pen and pencils are related to the number that can be bought

with a given amount of money.

  • <u />\underline{The \ ordered  \ pair \  (a,  \, b)  \ is  \ (6, \,  2)}<u />

Reasons:

The given parameters are;

If  the number number of pens and pencils James buys = 3 pens and 2 pencils, the amount James will have left = $2

If the number of pens and pencils James buys = 2 pens and 3 pencils, the amount James will have left = $6

The amount of money Judith has = The amount of money with James

The number of pens and pencil James and Judith can buy = 6 pens and 6 pencils

The cost of one pen = a

The cost of one pencil = b

Required:

To find the ordered pair (a, b)

Solution:

Let <em>X</em> represent the initial amount of money James has, we get;

X - (3·a + 2·b) = 2...(1)

X - (2·a + 3·b) = 6...(2)

2·X = 6·a + 6·b...(3)

Therefore;

X = (6·a + 6·b) ÷ 2 = 3·a + 3·b

Which from equation (1) gives;

3·a + 3·b - (3·a + 2·b) = 2

3·a + 3·b - 3·a - 2·b = 2

3·b - 2·b = 2

b = 2

Subtracting equation (1) from equation (2) gives;

(X - (2·a + 3·b)) - (X - (3·a + 2·b)) = 6 - 2 = 4

-2·a - 3·b + 3·a + 2·b = 4

a - b = 4

a = 4 + b

∴ a = 4 + 2 = 6

a = 6

<u />

<u />

\underline{The \ ordered  \ pair \  (a,  \, b)  \ is  \ (6, \,  2)}<u />

Learn more about word problems and simultaneous equations here:

brainly.com/question/14294864

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2 years ago
Which of the following is not a true statement? *
ANEK [815]

Answer:

b. The boundary line of y < 2x - 3 is not a solid line.

Step-by-step explanation:

It's a linear inequality thus its boundary line must be a solid line.

5 0
3 years ago
Find the equivalent exponential expression (7^2)^5
VladimirAG [237]
First we simplify, like this: (7^2)^5 = 7^{10}

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6 0
3 years ago
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A student who is trying to write a paper for a course has a choice of two topics, a and
Kitty [74]
Say she chooses topic A. She needs at least one book to arrive on time. The probability that no books arrive on time is 0.1 x 0.1 = 0.01 so the probability that at least one book arrives on time is 1 - 0.01 = 0.99.
Say she chooses topic B. She needs at least two books to arrive on time. The probability of no books arriving on time is 0.1 x 0.1 x 0.1 x 0.1 = 0.0001. The probability of exactly one book arriving on time is 4 x 0.1 x 0.1 x 0.1 x 0.9 = 0.0036 (binomial probability distribution formula - the 4 comes from 4C1). So the probability of her not getting enough books is 0.0001 + 0.0036 = 0.0037 and the probability she does get the books she needs on time is 1 - 0.0037 = 0.9963.
So she should choose topic B.
4 0
3 years ago
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