Verified Answer :

caylus

Hello,

a(1)=7=9-21
a(2)=5=9-22
a(3)=3=9-23
..
a(n)=?=9-2n

Answer C







apologiabiology

an=a1+d(n-1)
an=nth term
a1=first term
d=common difference

7 is first term=a1
the common difference is -2, they increase by -2 each time
an=7-2(n-1)
expand and distribute
an=7-2n+2
an=9-2n

C is answer

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