SOLUTION: I would like help in finding how to get the exponential function of the form f(x) = ab^x for which F(0) =15 and if f(-1) =10 Thank you!

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: I would like help in finding how to get the exponential function of the form f(x) = ab^x for which F(0) =15 and if f(-1) =10 Thank you!      Log On


   

Question 691894: I would like help in finding how to get the exponential function of the form f(x) = ab^x for which F(0) =15
and if f(-1) =10
Thank you!
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
f(x) = ab^x

f(0) = ab^(0)

f(0) = ab

15 = ab

b = 15/a

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f(x) = ab^x

f(-1) = ab^(-1)

f(-1) = a/b^1

f(-1) = a/b

10 = a/b

10 = a/(15/a)

10 = (a^2)/15

10*15 = a^2

150 = a^2

a^2 = 150

a = +-sqrt(150)

a = +-5*sqrt(6)

a = 5*sqrt(6) or a = -5*sqrt(6)

Now use these values of 'a' to find the values of 'b'.