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# help, function notation

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the table below shows the yearly sales of a cd player in a store

year          1         2          3          4         5        6

sales       55       100      145      190     235    280

find an equation in function notation for the relation

Oct 22, 2017

#1
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Notice how each year, the sales go up by  45 .

year 1 sales  =  55

year 2 sales  =  55 + 45

year 3 sales  =  55 + 45 + 45

year 4 sales  =  55 + 45 + 45 + 45

year 5 sales  =  55 + 45 * 4

year " x " sales  =  55 + 45 * (x - 1)

f(x)  =  55 + 45(x - 1)   where  x  is the year and  f(x)  is the sales. We can simplify the right side.

f(x)  =  55 + 45x - 45

f(x)  =  10 + 45x

Oct 22, 2017
edited by hectictar  Oct 22, 2017

#1
+1

Notice how each year, the sales go up by  45 .

year 1 sales  =  55

year 2 sales  =  55 + 45

year 3 sales  =  55 + 45 + 45

year 4 sales  =  55 + 45 + 45 + 45

year 5 sales  =  55 + 45 * 4

year " x " sales  =  55 + 45 * (x - 1)

f(x)  =  55 + 45(x - 1)   where  x  is the year and  f(x)  is the sales. We can simplify the right side.

f(x)  =  55 + 45x - 45

f(x)  =  10 + 45x

hectictar Oct 22, 2017
edited by hectictar  Oct 22, 2017
#2
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thank you did you mean f(x)=100+45x

Oct 22, 2017
#3
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No..if it was  f(x) = 100 + 45x , then for year 1 the sales would be  f(1) = 100 + 45(1) = 145

But for year 1, the sales are  10 + 45(1)  =  55, which agrees with the table. hectictar  Oct 22, 2017