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What is the closed linear form of the sequence 5, 7.5, 10, 12.5, 15,...

A) an = 5 + 2.5n

B) an = 5 - 2.5n

C) an = 2.5 + 2.5n

D) an = 2.5 - 2.5n

Respuesta :

luisejr77

Answer: Option C)

[tex]a_n = 2.5 + 2.5n[/tex]

Step-by-step explanation:

Note that the sequence increases by a factor of 2.5, that is, each term is the sum of the previous term plus 2.5.

[tex]7.5 - 5 = 2.5\\\\10 -7.5 = 2.5\\\\12.5 -10 = 2.5[/tex]

therefore this is an arithmetic sequence with an increase factor d = 2.5

The linear formula for the sequence [tex]a_n[/tex] is:

[tex]a_n = a_1 + d(n-1)[/tex]

Where

[tex]d = 2.5\\\\a_1 = 5[/tex]

[tex]a_1[/tex] is the first term of the sequence

So

[tex]a_n = 5 + 2.5(n-1)[/tex]

[tex]a_n = 2.5 + 2.5n[/tex]

The answer is the option C)

kudzordzifrancis

ANSWER

C)

[tex]a_n=2.5+2.5n[/tex]

EXPLANATION

The given sequence is:

5, 7.5, 10, 12.5, 15,...

where

[tex]a_1=5[/tex]

The constant difference is:

[tex]d = 7.5 - 5 = 2.5[/tex]

The closed linear form is given by;

[tex]a_n=a_1+d(n-1)[/tex]

We substitute the values into the formula to get:

[tex]a_n=5+2.5(n-1)[/tex]

Expand to get;

[tex]a_n=5+2.5n - 2.5[/tex]

[tex]a_n=2.5+2.5n[/tex]

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