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HELP PLEASE!!!


What’s the recursive and explicit formula for an arithmetic sequence we a1=2 and d=-4 ?

Respuesta :

gmany

The explicid formula of an arithmetic sequence:

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

We have

[tex]a_1=2,\ d=-4[/tex]

Substitute:

[tex]a_n=2+(n-1)(-4)[/tex]        use distributive property

[tex]a_n=2+(-4n)+(-1)(-4)\\\\a_n=2-4n+4\\\\\boxed{a_n=6-4n}[/tex]

The recursive formula of an arithmetic sequence:

[tex]\left\{\begin{array}{ccc}a_1=a_1\\a_n=a_{n-1}+d\end{array}\right[/tex]

Substitute:

[tex]\left\{\begin{array}{ccc}a_1=2\\a_n=a_{n-1}-4\end{array}\right[/tex]