Select the recursive and explicit formula for the Arnold family 2 answers
1 answer:
Answer: The first and last options are correct
Explanation:
The recursive formula is written in terms of the previous term of the sequence. From the information given,
the Arnold's are going to save a nickel on the first day of the month and double the amount each day of the month. Thus, the recursive formula would be
where
an - 1 defines a previous term
To write the explicit formula, we would apply the formula for finding the nth term of an arithmetic sequence which is expressed as
An = ar^(n - 1)
where
a is the first term of the sequence
n is the number of terms
r is the common ratio between consecutive terms
Thus,
r = 2 because the amount is doubling each day
n = number of days
a = value of 1 nickel = $0.05
By substituting these values into the formula,
the explicit formula is
A(n) = 0.05(2)^n - 1
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Answer:
b.
Step-by-step explanation:
We have to look at sign changes in f(x) to determine the possible positive real roots.
There is only one sign change here, between the -8x and the +4. So that means there is only 1 possible real positive root.
Now we have to look at sign changes in f(-x) to determine the possible negative real roots.
There are 3 sign changes here. That means there are either 3 negative roots or 3-2 = 1 negative root. So we have:
1 positive
3 or 1 negative
We need to pair them up now with all the possible combinations.
If we have 1 positive and 1 negative, we have to have 2 imaginary
If we have 1 positive and 3 negative, we have to have 0 imaginary
Keep in mind that the total number or roots--positive, negative, imaginary--have to add up to equal the degree of the polynomial. This is a 4th degree polynomial, so we will have 4 roots.