Question 62910
In 2000, about 33.1 billion photos were printed from film and that number was declining at a rate of 1.1 billion per year. There were 2.8 billion digital photos printed or stored in 2000 and that number was growing at a rate of 2.9 billion per year. 
a) Write two equations that can be used to predict n, the number of filmed or digital photos, in billions, t years after 2000.
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For photos you have a point (0,33.1) and a slope= (1.1)
You need an equation:
n=(slope)t+b
33.1=1.1(0)=b
b=33.1
EQUATION:
n=1.1t+33.1 (n in billions)
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For digital photos you have a point (0,2.8) and slope=2.9
EQUATION
n=2.9t+2.8 (n in billions)
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b) Use a graphing calculator to determine the year in which the numbers of filmed photos and digital photos are the same. 
{{{graph(300,200,-10,20,-10,60, 2.9x+2.8,1.1x+33.1 )}}}
Intersection at (16.833333,51.616666..)
Cheers,
Stan H.