Find a formula for the exponential function passing through the points (-1,2/3) and (1,6) Help much apprieciated can't figure this one out.

evanborot Nov 29, 2019

#1**+1 **

Find a formula for the exponential function passing through the points (-1,2/3) and (1,6) Help much apprieciated can't figure this one out.

Omi67 Nov 29, 2019

#2**+2 **

Here's another approach

We have the form

y = ab^x

When x = -1, y = 2/3

When x = 1, y = 6

So we have that

2/3 = ab^(-1) (1)

6 = ab^(1) ⇒ ab = 6 ⇒ b = 6/a (2)

Sub (2) into (1) and we have that

(2/3) = a ( 6/a)^(-1)

2/3 = a ( a /6) multiply through by 6

4 = a^2 take the positive root

2 = a

So b = 6/2 = 3

So....the function is

y = 2 (3)^x

Here's a praph :

https://www.desmos.com/calculator/mmoq0kzrez

CPhill Nov 29, 2019