Nail Length

Section 3.3
Question 88

Note: I am using Example 7 as a guide for me to work out 88.





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 = 0.113.

So, (ln 2, ln 0.113) becomes (0.693, -2.180).

I now must find the slope m using (0.693, -2.180) and the origin.

m = (-2.180 - 0)/(0.693 - 0)

m = -2.180/0.693

m = -3.1457431457

Rounding to two decimal places, I get m = -3.15.

I know use the point-slope formula.

y - y_1 = m(x - x_1)

I will use the point (0, 0).

y - 0 = -3.15(x - 0)

y = -3.15x

I say the logarithmic equation is y = -3.15 ln x.

You say?

 

why did you choose (0,0) as a second point?

 

I selected (0, 0) following Example 7. If wrong, which two points should I have chosen?

 

ok

 

Is my equation right or wrong?

 

in Example 7 ,
if x=1 and y=1 (from given table) then (ln(x), ln(y)) =(ln(1), ln(1)) =(0, 0)
if x=1.524 and y=1.881 (from given table) then (ln(x), ln(y)) =(ln(1.524), ln(1.881)) =(0.421, 0.632)
then was calculated slope

since fig. 3.14 cannot be used for 88, and you have to use two of given points from the table
so, your equation is incorrect

 

Thanks for letting me know. I now know what to do.

Note: Visit the Algebra forum here. There are 7 or 8 unanswered threads there.