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Sergeu [11.5K]
2 years ago
13

Find a formula for the sum of the first n even integers : 2 + 4 + 6 + ... + 2n.

Mathematics
1 answer:
Sedbober [7]2 years ago
7 0

Let S be the sum,

S = 2 + 4 + 6 + ... + 2 (n - 2) + 2 (n - 1) + 2n

Reverse the order of terms:

S = 2n + 2 (n - 1) + 2 (n - 2) + ... + 6 + 4 + 2

Add up terms in the same positions, so that twice the sum is

2S = (2n + 2) + (2n + 2) + (2n + 2) + ... + (2n + 2)

or

2S = n (2n + 2)

Divide both sides by 2 to solve for S :

S = n (n + 1)

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Answer:

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Step-by-step explanation:

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The common factors are 2, 2, and 5. We multiply those to get the GCF.

2 × 2 × 5 = 20

7 0
3 years ago
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NeTakaya

Answer:

D

Step-by-step explanation:

The formula we need to solve this is:

d_1+d_2=2a

Where

d_1  is the distance from one focus to the vertex

d_2  is the second distance from another focus to same vertex

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<em>Now we can plug into the equation and solve:</em>

<em>d_1+d_2=2a\\8.5+d_2=2(9)\\8.5+d_2=18\\d_2=18-8.5\\d_2=9.5</em>

<em />

<em>D is the correct answer.</em>

6 0
4 years ago
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I believe the answer is false.

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Paulo uses an instrument called a densitometer to check that he has the correct ink colour.
tia_tia [17]
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If we add this value to the original value,
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If we subtract this value from the original value,
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3 years ago
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Answer:

The total price is $862.92, the tax is $63.92.

Step-by-step explanation:

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