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kirza4 [7]
2 years ago
13

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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<em>It took 31 days for the patch to cover half the lake</em>

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Step-by-step explanation:

The patch grows to double its size everyday

the patch completely covers the lake in 32 days

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

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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
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The number of possible codes is this:
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6 0
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