Q. Write an explicit formula that represents the sequence defined by the following recursive formula:a1=100 and an=−51an−1Answer: an=
Identify Pattern: To find an explicit formula for the sequence, we start by looking at the first few terms to identify a pattern.Given a1=100, we can find a2 using the recursive formula an=−51an−1.a2=−51a1=−51×100=−20
Calculate a2: Next, we find a3 using the same recursive formula.a3=−51a2=−51×(−20)=4
Calculate a3: We continue this process to find a4.a4=−51a3=−51×4=−0.8
Find a4: From the pattern, we can see that each term is −51 times the previous term. This is a geometric sequence with the first term a1=100 and common ratio r=−51. The explicit formula for a geometric sequence is an=a1⋅r(n−1). Substituting the values we have, we get an=100⋅(−51)(n−1).