# need help

• Jan 22nd 2008, 08:03 PM
mathlete
need help
Table 1.9 shows some values of a linear function f and an exponential function g. Find exact values (not decimal approximations) for each of the missing entries of f, and round your answers for g to 3 decimals.

Table1.9 x 0 1 2 3 4

f(x) 15 30
g(x) 15 30

mathlete
• Jan 22nd 2008, 10:54 PM
CaptainBlack
Quote:

Originally Posted by mathlete
Table 1.9 shows some values of a linear function f and an exponential function g. Find exact values (not decimal approximations) for each of the missing entries of f, and round your answers for g to 3 decimals.

Code:

Table1.9 x 0  1  2  3  4 f(x)        15    30  g(x)        15    30

mathlete

$\displaystyle f(x)=mx+c$

determine $\displaystyle m$ and $\displaystyle c$ from the given data, and then fill in the missing values.

$\displaystyle g(x)=A e^{kx}$

determine $\displaystyle A$ and $\displaystyle k$ from the given data, and then fill in the missing values. This may be simplified by taking logs when you have:

$\displaystyle \ln(g(x))=k \ln(x) + \ln(A)$

RonL
• Jan 23rd 2008, 04:12 AM
a tutor

As I said there, you don't need to find the equations.

f(2)-f(1)=f(1)-f(0)

g(2)/g(1)=g(1)/g(0)
• Jan 23rd 2008, 04:44 AM
CaptainBlack
Quote:

Originally Posted by a tutor

As I said there, you don't need to find the equations.

f(2)-f(1)=f(1)-f(0)

g(2)/g(1)=g(1)/g(0)

Indeed you don't, but this won't work as it is either since the functional values at 1 and 3 are given not 0 and 2;
or are they - difficult to tell from the original question :(

RonL
• Jan 23rd 2008, 04:54 AM
janvdl
Quote:

Originally Posted by CaptainBlack
Indeed you don't, but this won't work as it is either since the functional values at 1 and 3 are given not 0 and 2;
or are they - difficult to tell from the original question :(

RonL

On quoting it seems they are at 0 and 2, Captain. (Nod)
• Jan 23rd 2008, 04:54 AM
a tutor
Quote:

Originally Posted by CaptainBlack
the functional values at 1 and 3 are given not 0 and 2;
or are they - difficult to tell from the original question :(

It is hard to tell. I took them to be values for x=0 and x=1.

In any case you can just use $\displaystyle \sqrt{\frac{g(3)}{g(1)}}$ if the values were x=1 and x=3.