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2 years ago

Find the 21st term of the sequence 15,8,1,-6

Mathematics

1 answer:

Alika [10]2 years ago

7 0

Answer:

-125

Step-by-step explanation:

Each term is 7 less than the previous term.

1st term: 15

2nd term: 15 - 7

3rd term: 15 - 7 - 7 = 15 - 2(7)

4th term = 15 - 7 - 7 - 7 = 15 - 3(7)

Notice that each term is 15 minus a multiple of 7. The multiple is obtained by multiplying 7 by 1 less than the term number.

The formula is:

$a_n = 15 - 7(n - 1)$

For the 21st term, multiply 7 by 20, and subtract from 15.

7 × 20 = 140

15 - 140 = -125

Using the formula:

$a_{21} = 15 - 7(21 - 1) = 15 - 7(20) = 15 - 140 = -125$

Answer: -125

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3 years ago

A lake has a small patch of lily pads and every day the patch grows to double its size. It takes 32 days for the patch to cover

S_A_V [24]

Answer:

It took 31 days for the patch to cover half the lake

Step-by-step explanation:

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Therefore, the the patch covered half the lake on the 31st day, i.e it took 31 days for the patch to cover half the lake

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3 years ago

Simplify f+g / f-g when f(x)= x-4 / x+9 and g(x)= x-9 / x+4

steposvetlana [31]

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$\dfrac{f+g}{f-g}=(f+g):(f-g)=\dfrac{2x^2-97}{(x+9)(x+4)}:\dfrac{65}{(x+9)(x+4)}\\\\=\dfrac{2x^2-97}{(x+9)(x+4)}\cdot\dfrac{(x+9)(x+4)}{65}\\\\Answer:\ \boxed{\dfrac{f+g}{f-g}=\dfrac{2x^2-97}{65}}$

6 0

3 years ago

Read 2 more answers

THERE IS MORE THAN ONE ANSWER THEIR IS UP TO 3 ANSWERS

kvv77 [185]

Answer:

-4.01, -4, -7

Step-by-step explanation:

equation:

-x + 6 ≥ 10

substitute each number for x

- (-3.9) + 6 ≥ 10 = (negatives cancel each other out) 3.9 + 6 = 9.9 ≥ 10 (incorrect)

-4 + 6 ≥ 10 = 2 ≥ 10 (incorrect)

- (-4.01) + 6 ≥ 10 = (negatives cancel each other out) 10.01 ≥ 10 (correct)

- (-4) + 6 ≥ 10 = (negatives cancel each other out) 10 ≥ 10 (correct)

-4.01 + 6 ≥ = 1.99 ≥ 10 (incorrect)

-3.9 + 6 ≥ 10 = 2.1 ≥ 10 (incorrect)

-0 + 6 ≥ 10 = 6 ≥ 10 (incorrect)

- (-7) + 6 ≥ 10 = (negatives cancel each other out) 11 ≥ 10 (correct)

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3 years ago

A word processing program requires a user to enter a 7-digit registration code made up of the digits 1,2,4,5,6,7 and 9. Each num

ahrayia [7]

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The number of possible codes is this:
7*6*5*4*3*2*1 = 7! = 5040

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3 years ago