Topic: Recognizing Linear and Exponential and Quadratic Functions.
1 answer:
Answer:
Recursive: f(1) = 1; f(n) = f(n-1)/3
Equation: f(x) = 5/3·(1/3)^(x-1)
Step-by-step explanation:
You know this is an exponential function because sequential lines in the table have a common ratio of f(x) values:
f(2)/f(1) = (5/9)/(5/3) = 3/9 = 1/3
f(3)/f(2) = (5/27)/(5/9) = 9/27 = 1/3
and it continues like that.
Besides telling you the function is exponential, it also tells you that each term is 1/3 of the previous term.
<h3>Recursive formula</h3>The value of f(1) is read from the table. For x = 1, that value is ...
f(1) = 5/3
As we noticed above, each term is 1/3 the previous term, so the recursive relation is ...
f(n) = (1/3)·f(n-1)
<h3>Equation</h3>The general form of the equation for a geometric (exponential) relation is ...
f(x) = f(1)·r^(x-1) . . . . . . where f(1) is the first term, and r is the common ratio
For this function, we have f(1) = 5/3 and r = 1/3, so the equation is ...
f(x) = 5/3·(1/3)^(x-1)
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<em>Additional comment</em>
When given values of x that count from 1, we often express the equation in terms of (x-1). That equation can be simplified so the exponent is x.
f(x) = 5·(1/3)^x
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In the second store, if Darin bought tiles, he would need to spend:
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For the cost to be the same at both stores, it means (measured in $)
Moving
over to the left hand side and changing signs:
tiles
Let's check. If he buys 60 tiles in the first store, he spends:
$0.79×60 + $24 = $47.40 + $24 = $71.40
If he buys 60 tiles in the second store, he spends:
$1.19×60 = $71.40
∴ Darin needs to buy 60 tiles for the cost to be the same at both stores.
In the first store, if Darin bought
In the second store, if Darin bought
For the cost to be the same at both stores, it means (measured in $)
Moving
Let's check. If he buys 60 tiles in the first store, he spends:
$0.79×60 + $24 = $47.40 + $24 = $71.40
If he buys 60 tiles in the second store, he spends:
$1.19×60 = $71.40
∴ Darin needs to buy 60 tiles for the cost to be the same at both stores.