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How do you find the value of an exponential function that is f(x)=ab^x and if f(5)=96 and f(7)=384. positive constants

 Jun 11, 2014

Best Answer 

 #1
avatar+130513 
+5

We have

96 = ab5        and  384 = ab7    Using the first, we have 96/b = a

Substituting into the second, we have

384 = (96/b) b7    simplifying, we have

384 = 96b2      divide both sides by 96

384/96 =  b2

4 = b2

2 = b     and using  ..... 96/b = a     ... we have     96/(2)5 = a    96/32 = a  = 3

So....our function is .... f(x) =  3(2x)

 Jun 11, 2014
 #1
avatar+130513 
+5
Best Answer

We have

96 = ab5        and  384 = ab7    Using the first, we have 96/b = a

Substituting into the second, we have

384 = (96/b) b7    simplifying, we have

384 = 96b2      divide both sides by 96

384/96 =  b2

4 = b2

2 = b     and using  ..... 96/b = a     ... we have     96/(2)5 = a    96/32 = a  = 3

So....our function is .... f(x) =  3(2x)

CPhill Jun 11, 2014

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