Answer:
[tex]a_n = -11-14n[/tex]
Step-by-step explanation:
Given
[tex]a_1 = -25[/tex]
[tex]a_n = a_{n-1}-14[/tex]
Required
The explicit formula
First, calculate [tex]a_2[/tex]
Set n=2; So:
[tex]a_2 = a_{2-1}-14[/tex]
[tex]a_2 = a_{1}-14[/tex]
Substitute -25 for [tex]a_1[/tex]
[tex]a_2 = -25-14[/tex]
[tex]a_2 = -39[/tex]
Calculate the common difference (d)
[tex]d = a_2 - a_1[/tex]
[tex]d = -39 --25[/tex]
[tex]d = -14[/tex]
So, the nth term is:
[tex]a_n = a_1 + (n - 1)d[/tex]
[tex]a_n = -25+ (n - 1)*-14[/tex]
Open bracket
[tex]a_n = -25-14n + 14[/tex]
Collect like terms
[tex]a_n = 14-25-14n[/tex]
[tex]a_n = -11-14n[/tex]
