Q. {f(1)=4,f(n)=f(n−1)⋅(−0.5) Find an explicit formula for f(n).f(n)=
Given Recursive Formula: Given the recursive formula for a sequence: f(1)=4 and f(n)=f(n−1)×(−0.5) for n > 1. We need to find an explicit formula for f(n).
Observing Pattern of Sequence: To find an explicit formula, let's observe the pattern of the sequence for the first few terms. Starting with f(1)=4:- f(2)=f(1)×(−0.5)=4×(−0.5)=−2- f(3)=f(2)×(−0.5)=−2×(−0.5)=1- f(4)=f(3)×(−0.5)=1×(−0.5)=−0.5
Identifying Exponential Pattern: Notice the pattern in the sequence: 4,−2,1,−0.5,ext... Each term is obtained by multiplying the previous term by −0.5. This suggests an exponential pattern with a base of −0.5 and a starting value of 4 when n=1.
General Form of Exponential Function: The general form for an exponential function is f(n)=a⋅b(n−1), where a is the initial value, b is the base of the exponential, and n is the term number. In our case, a=4 (the first term) and b=−0.5 (the factor by which each term is multiplied to get the next term).
Substituting Values into Formula: Substituting the values of a and b into the general form, we get the explicit formula for the sequence as f(n)=4×(−0.5)(n−1).
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