Question 118944
Ans. As the sequence is (7,-1,-9,-17...) the first term clearly is 7.

Let it be t1.thus t1=7
if we let second term as t2 then t2=-1 and if we let third term as t3 then t3=-9.
Let nth term be tn.

Now considering the sequence as arithmetic sequence, we know that for any arithmetic sequence the nth term is given by tn=t1+(n-1)d, where d is constant difference between consecutive terms.

Thus here tn=7+(n-1)-8[As difference d here is -8,t2-t1=-1-7=-8]
thus tn=7-8(n-1)
thus tn=7-8n+8
thus tn=15-8n.

Thus ans is tn=15-8n. Thus this function best describes the above sequence.

[Note: here we have considered the sequence to be arithmetic one]