Math

posted by .

if f is an exponential function, and f(5)=20 and f(9) = 14, use the add-multiply property to calculate f(13),f(17), and f(21). Show your method

  • Math -

    there is a difference of x=+4 between 5, 9
    There is a multiply difference of 14/20=.7 between the two.

    f(13)=14*.7
    f(17)=14*.7*.7
    f(21)=14(.7*.7*.7)

  • Math -

    let f(x) = a(b^x) or
    y = a(b^x)
    given: when x=5, y=20
    20 = a b^5
    given: when x=9, y=14
    14 = a b^9
    divide the 2nd by the first:
    b^4 = 14/20 = 0.7
    b = (0.7)^.25 = appr .91469
    sub into 20 = a b^5
    20 = a(.91469)^5
    a = 31.236
    f(x) = 31.236 (.91469)^x

    f(13) = 31.236(.91469)^13 = 9.8
    you do the button-pushing for the rest

    Note, I used the memory locations of my calculator to store all the supplied decimal values for both a and b

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Distributive property

    How would I multiply these expression? 6(h-4) -3(x+8) -10(-a+5) PLease and thank-You Multiply the coefficient (outside the parentheses) by each term inside the parentheses. For example, 6(h-4) = 6h - 24 You do the others do you have
  2. Calculus

    Given y=log(x), what is dy/dx? If you have to derive this from first principles, then you have to use the defintion of the Logarithm. E.g. you could use that the Logarithm is the inverse of the exponential function and that the derivative
  3. 5th Grade math

    What is a partial-products algorithm. For example 87*65=?
  4. algebra 2

    It says to: Use the Distributive Property to show that the following are true statements: 8.5m + 1.3m = 9.8m What does it mean to use the distributive property?
  5. Math

    Let f(t) be an exponential function with f(0) = 11 and f(4) = 59. Use the form f(t) = Pa^t to find an equation for this exponential function?
  6. math-5

    Tara spent 3 hours doing homework. She spent 1/3 of her time on math, and 1/5 on science. Which method would provide the most reasonable estimate of the totaltime Tara spent on her math and science homework?
  7. math-5

    Which choice is the answer? Show me please. Tara spent 3 hours doing homework. She spent 1/3 of her time on math, and 1/5 on science. Which method would provide the most reasonable estimate of the totaltime Tara spent on her math and
  8. Math. idk?

    6. Name the like terms in the following expression. 5m + 4 + 3m + 6p 7. Write an equation for the following: Twelve times h equals one hundred twenty minus thirty-six.State whether the equation is true, false, or an open sentence. …
  9. Math question? :c

    Use the Distributive Property to multiply. Show all steps. 7(c + 4)
  10. Distributive Property Algebra

    I have two questions I don't understand and I need you to explain the steps of each problem to me?

More Similar Questions