Download presentation

Presentation is loading. Please wait.

1
**8.7 Modeling with Exponential & Power Functions**

How do you write an exponential function given two points? How do you write a power function given two points? Which function uses logs to solve it?

2
**Just like 2 points determine a line, 2 points determine an exponential curve.**

3
**Write an Exponential function, y=abx whose graph goes thru (1,6) & (3,24)**

Substitute the coordinates into y=abx to get 2 equations. 1. 6=ab1 2. 24=ab3 Then solve the system:

4
**Write an Exponential function, y=abx whose graph goes thru (1,6) & (3,24) (continued)**

1. 6=ab1 → a=6/b 2. 24=(6/b) b3 24=6b2 4=b2 2=b a= 6/b = 6/2 = 3 So the function is Y=3·2x

5
**Write an Exponential function, y=abx whose graph goes thru (-1,**

b(.0625)=a 32=[b(.0625)]b2 32=.0625b3 512=b3 b=8 y=1/2 · 8x a=1/2

6
**Modeling with POWER functions**

a = 5/2b 9 = (5/2b)6b 9 = 5·3b 1.8 = 3b log31.8 = log33b .535 ≈ b a = 3.45 y = 3.45x.535 y = axb Only 2 points are needed (2,5) & (6,9) 5 = a 2b 9 = a 6b

7
**You can decide if a power model fits data points if:**

(lnx,lny) fit a linear pattern Then (x,y) will fit a power pattern See Example #5, p. 512 You can also use power regression on the calculator to write a model for data.

8
**How do you write an exponential function given two points?**

y = abx How do you write a power function given two points? y = axb Which function uses logs to solve it? Power function y = axb

9
Homework Page 513 17-22, 29-35

Similar presentations

OK

EXAMPLE 1 Write a quadratic function in vertex form Write a quadratic function for the parabola shown. SOLUTION Use vertex form because the vertex is given.

EXAMPLE 1 Write a quadratic function in vertex form Write a quadratic function for the parabola shown. SOLUTION Use vertex form because the vertex is given.

© 2018 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google