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PLEASE HELP
Which expression defines the arithmetic series 1 + 5 + 9 + ... for seven terms?
Σ(27-1)
Σ(3n-4)
Σ(4n-3)
Σ(n-1)

PLEASE HELP Which expression defines the arithmetic series 1 5 9 for seven terms Σ271 Σ3n4 Σ4n3 Σn1 class=

Respuesta :

MrRoyal

Answer:

[tex]\sum\limits^7_{n=1}(4n - 3)[/tex]

Step-by-step explanation:

Given

[tex]1 + 5 + 9 + .....[/tex]

Required

Write a definition

First, we derive a formula for the series using:

[tex]T_n = a + (n - 1)d[/tex]

From the attached data;

[tex]a = 1[/tex]

[tex]d = 5 - 1 = 4[/tex]

So:

[tex]T_n = a + (n - 1)d[/tex]

[tex]T_n = 1 + (n - 1) * 4[/tex]

[tex]T_n = 1 + 4n - 4[/tex]

Collect like terms

[tex]T_n = 4n - 4+1[/tex]

[tex]T_n = 4n -3[/tex]

So, the definition for first 7 terms is:

[tex]\sum\limits^7_{n=1}(4n - 3)[/tex]

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