Use function notation to write a recursive formula to represent the sequence: 3, 6, 9, …
1 answer:
Answer:
f(n) = f(n - 1) + 3
Step-by-step explanation:
Substitute to get the recursive formula.
OPTION 1: f(n) = f(n - 1) + 3
Substituting n = 1.
f(1) = f(1 - 1) + 3 = 0 + 3 = 3.
Substituting n = 2.
f(2) = f(2 - 1) + 3 = f(1) + 3 = 3 + 3 = 6.
Substituting n = 3.
f(3) = f(3 - 1) + 3 = f(2) + 3 = 6 + 3 = 9.
The numbers match the given sequence. So, we say the above recursive formula represents the sequence.
OPTION 2: f(n) = f(n - 1) + 2
Substituting n = 1
f(1) = f(0) + 2 3.
So, this is eliminated.
Similarly, OPTION 3 and OPTION 4 can be eliminated as well.
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Answer:
(x, y) = (1, -1)
Step-by-step explanation:
We'll write these equations in general form, then solve using the cross-multiplication method.
43x +67y +24 = 0
67x +43y -24 = 0
∆1 = (43)(43) -(67)(67) = -2640
∆2 = (67)(-24) -(43)(24) = -2640
∆3 = (24)(67) -(-24)(43) = 2640
These go into the relations ...
1/∆1 = x/∆2 = y/∆3
x = ∆2/∆1 = -2640/-2640 = 1
y = ∆3/∆1 = 2640/-2640 = -1
The solution is (x, y) = (1, -1).
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<em>Additional comment</em>
The cross multiplication method isn't taught everywhere. The attachment explains a bit about it. Our final relationship changes the order of the fractions to 1, x, y from x, y, 1. That way, we can use the equation coefficients in their original general-form order. (The fourth column in the 2×4 array of coefficients is a repeat of the first column.)
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