Q. Write an explicit formula that represents the sequence defined by the following recursive formula:a1=4 and an=an−1+5Answer: an=
Identify Pattern: To find the explicit formula for the sequence, we need to determine a pattern that can be applied directly to find any term in the sequence without having to find all the previous terms.
Find First Terms: Let's start by finding the first few terms of the sequence using the recursive formula:a1=4 (given)a2=a1+5=4+5=9a3=a2+5=9+5=14a4=a3+5=14+5=19From this pattern, we can see that each term is 5 more than the previous term.
Analyze Relationship: Now, let's look at the relationship between the term number n and the value of each term: a1=4=4+5(1−1)a2=9=4+5(2−1)a3=14=4+5(3−1)a4=19=4+5(4−1) We can see that the term value is equal to the first term 4 plus 5 times (n−1).
Determine Explicit Formula: The pattern suggests that the explicit formula for the nth term is:an=4+5(n−1)This formula allows us to calculate the value of any term directly.
Verify Formula: To verify that this formula is correct, let's test it with n=5: a5=4+5(5−1)=4+5(4)=4+20=24 Now, let's check it with the recursive definition: a5=a4+5=19+5=24 Both methods give us the same result, confirming that our explicit formula is correct.
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