# Curve Fitting

Discussion in 'Other Pre-University Math' started by nycmathguy, Oct 20, 2021.

1. ### nycmathguy

Joined:
Jun 27, 2021
Messages:
5,386
422
Section 3.3
Question 83

Note: I am going to use Example 7 as a guide for me to do 83. Question 83 I have to use the given information in the box above to find at least one point in the form
(ln x, ln y).

I will use x = 2, y = 1.189

So, (ln 1, ln 0.5) becomes (0.693, 0.173).

I now must find the slope m using (0.693, 0.173) and the origin.

m = (0.173 - 0)/(0.693 - 0)

m = 0.173/0.693

m = 0.2496392496

Rounding to two decimal places, I get m = 0.25.

I know use the point-slope formula.

y - y_1 = m(x - x_1)

I will use the point (0, 0).

y - 0 = 0.25(x - 0)

y = 0.25

I say the logarithmic equation is y = 0.25 ln x.

You say?

nycmathguy, Oct 20, 2021
2. ### MathLover1

Joined:
Jun 27, 2021
Messages:
2,989
2,884
why did you use point (0,0)? I do not see figure 3.14.

Last edited: Oct 20, 2021
MathLover1, Oct 20, 2021
nycmathguy likes this.
3. ### nycmathguy

Joined:
Jun 27, 2021
Messages:
5,386
422
I selected the point (9, 0) following Example 7. As a matter of fact, after checking the answer in the of the textbook, I got it right.

You say?

Which two points should I have chosen?

nycmathguy, Oct 20, 2021
4. ### MathLover1

Joined:
Jun 27, 2021
Messages:
2,989
2,884
where is the point (9, 0) in Example 7?(I believe it was typo)

and you used point (0,0) to get m = (0.173 - 0)/(0.693 - 0)=0.25 which is correct

but, I do not see fig. 3.14 (in example 7) which they referring to while choosing two points to calculate the slope

Last edited: Oct 20, 2021
MathLover1, Oct 20, 2021
nycmathguy likes this.
5. ### nycmathguy

Joined:
Jun 27, 2021
Messages:
5,386
422
Here is figure 3.13 and 3.14: nycmathguy, Oct 21, 2021
6. ### MathLover1

Joined:
Jun 27, 2021
Messages:
2,989
2,884
there you go, now I see

MathLover1, Oct 21, 2021
nycmathguy likes this.
7. Joined:
Jun 27, 2021
Messages:
5,386