Q. An exponential function, f(x), passes through (4,−2) and (5,10) and has a horizontal asymptote at y=−8. What is an equation of f(x) ?f(x)=□
Identify Asymptote: An exponential function with a horizontal asymptote at y=−8 can be written in the form f(x)=a⋅bx+c, where c is the horizontal asymptote. So, c=−8.
Find Values of a and b: We have: f(x)=a⋅bx−8. Now we need to find the values of a and b using the points (4,−2) and (5,10).
Equation from Point (4,−2): Using the point (4,−2), we get the equation −2=a⋅b4−8. Adding 8 to both sides gives us a⋅b4=6.
Equation from Point (5,10): Using the point (5,10), we get the equation 10=a⋅b5−8. Adding 8 to both sides gives us a⋅b5=18.
Eliminate a to Solve for b: Now we have two equations: a⋅b4=6 and a⋅b5=18. We can divide the second equation by the first to eliminate a and solve for b.a⋅b4a⋅b5=618b=3
Substitute b to Find a: Now that we have b, we can substitute it back into one of the equations to find a. Using a⋅b4=6 and b=3, we get:a⋅34=6a⋅81=6a=816a=13.51
Final Exponential Function: Substituting a=13.51 and b=3 into f(x)=a⋅bx−8 gives us the final equation f(x)=(13.51)⋅3x−8.
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