Find a power function through the two points: (7,8) (1,0.7)

This is what I've gotten only:

I tried solving for p but it came out to be -1.25 and not 1.25 like the back of the book.

Thank you!

Printable View

- November 26th 2009, 08:39 PMhydridePower Functions
Find a power function through the two points: (7,8) (1,0.7)

This is what I've gotten only:

I tried solving for p but it came out to be -1.25 and not 1.25 like the back of the book.

Thank you! - November 26th 2009, 09:08 PMCaptainBlack
- November 26th 2009, 09:34 PMSoroban
Hello, hydride!

Quote:

Find a power function through the two points: (7, 8), (1, 0.7)

This is what I've gotten only:

I tried solving for p but it came out to be -1.25 . . . . How?

and not 1.25 like the back of the book.

Divide [1] by [2]: .

Take logs, base 7: .

. . Hence: .

Substitute into [1]: .

Therefore: . .*

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

*

- November 26th 2009, 09:39 PMhydride
How did you get k = .7?

Can you do it an alternate way? By using substitution? - November 27th 2009, 03:54 AMHallsofIvy
Here's how I would have done it:

From and we have immediately that k= .7. Put that into the first equation: so , approximately. Now take the logarithm of boht sides: and . - November 27th 2009, 08:07 AMhydride
- November 28th 2009, 11:02 PMgetevlcted
when you figured out that k was .7 in the second set p is not needed becuase 1 ^x = 1

you get the K and input it into the first set and get 8= (.7) (7)^n

hydride do you have fred at csuf? lol