Answer
In order for a sequence to be arithmetic, the difference of all consecutive terms must be constant.
Hence here: $a_{n+1}-a_n=(2(n+1)-5)-(2n-5)=(2n-3)-(2n-5)=2$, thus it is an arithmetic sequence.
$a_1=-3$
$a_2=-1$
$a_3=1$
$a_4=3$
Work Step by Step
In order for a sequence to be arithmetic, the difference of all consecutive terms must be constant.
Hence here: $a_{n+1}-a_n=(2(n+1)-5)-(2n-5)=(2n-3)-(2n-5)=2$, thus it is an arithmetic sequence.
$a_1=2(1)-5=-3$
$a_2=2(2)-5=-1$
$a_3=2(3)-5=1$
$a_4=2(4)-5=3$
