SOLUTION: Does y=11(8/13)^x represents exponential growth or exponential decay.

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Question 468317: Does y=11(8/13)^x represents exponential growth or exponential decay.
Answer by ccs2011(207) About Me  (Show Source):
You can put this solution on YOUR website!
Given the exponential function:
y+=+a%2Ab%5Ex
where a is a constant scale factor and b is the base raised to power of x.
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If b > 1, then as x increases so does y, thus its a growth function.
Ex:
a=1, b=2
y+=+2%5Ex
If x = 1, y = 2^1 = 2
If x = 3, y = 2^3 = 8
...
graph%28200%2C200%2C-1%2C5%2C-1%2C20%2C2%5Ex%29
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If b < 1, then as x increases y decreases, thus its a decay function.
Ex:
a=1, b=1/2
y+=+%281%2F2%29%5Ex
If x = 1, y = (1/2)^1 = 1/2
If x = 3, y = (1/2)^3 = 1/8
...
graph%28200%2C200%2C-1%2C5%2C-1%2C2%2C0.5%5Ex%29
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Remember:
b > 1 ---> Growth
b < 1 ---> Decay
You can always check by plugging in x_values as well, I suggest 0 and 1.
If the y_value went up then its growth, if not its decay.
Lets look at your problem y+=+11%288%2F13%29%5Ex
a= 11, b = 8/13
8/13 < 1 --> Decay
y+=+11%288%2F13%29%5E0+=+11
y+=+11%288%2F13%29%5E1+=+88%2F13+=+6.77
y decreased therefore we confirm the function is a decay function.