Question

Please Help!!! Confused on this one?

Find the 43rd term of sequence. 27, 24 21 18....

A. -102

B. -96

C.-99

D. -105

Answer 1

This is an arithmetic sequence. The first term,
`a_(1)`, is 27. The common difference is -3 (you subtract 3 from a number to get to the next number in line), and you are looking for term number 43, or
`a_(43)`. Your formula for an arithmetic sequence is
`a_(n)= a_(1) +d(n-1)`. If we are looking for term number 43, our first number in the sequence is 27, and the common difference is -3, then our formula is this one:
`a_(43) =27-3(43-1)`, which simplifies to
`a_(43)=27-3(42)`, which is
`a_(43)=27-126` and
`a_(43)=-99`