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The graph of y = 3(10)^x − 1 is shown. What are the x-intercept (rounded to the nearest tenth) and the horizontal asymptote, and do they represent exponential growth or decay?

 Feb 11, 2016
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Here's the graph : https://www.desmos.com/calculator/qgngrhqfqf

 

To find the x-intercept....let y = 0   and solve for x

 

0 = 3(10)^x  - 1      add 1 to both sides

 

1 = 3(10)^x             divide both sides by 3

 

1/3  = 10^x           take the log of both sides

 

log (1/3)  = log(10)^x       and we can write

 

log(1/3) = x log(10)         log(10) =  1   so we can ignore this

 

log(1/3)  = x  = about  -0.48

 

 

The horizontal asymptote   is   y = -1

 

This is a growth curve because as x grows larger, y grows larger

 

 

 

cool cool cool

 Feb 11, 2016
edited by CPhill  Feb 11, 2016

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