The first term of an arithmetic sequence is 14. The 25th term is 206. What is the common difference of the arithmetic sequence?

Respuesta :

an = a1+ d(n-1)

a1 =14

an=206  when n=25

206 = 14 + d (25-1)

206 = 14 + d * 24

subtract 14 from each side

192 = 24d

divide by 24 on each side

d=8

The common difference is 8

an atirmetic sequence  can be written in form

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

where [tex]a_n[/tex] is the nth term

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

[tex]d[/tex] is the common difference

[tex]n[/tex] is the counter variable


so, given that first term is 14 ([tex]a_1=14[/tex]) and given taht 25th term is 206 ([tex]a_{25}=206[/tex]), we want to find d


[tex]a_{25}=206[/tex]

[tex]a_{25}=a_1+d(25-1)[/tex]

[tex]206=14+24d[/tex]

minus 14 both sides

[tex]192=24d[/tex]

divide both sides by 24

[tex]8=d[/tex]

the common difference is 8

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