Math Is Fun Forum

T33N_T1T4N

Member

Registered: 2007-02-10

Posts: 8

exponential problem

Given the coordinates (2, 10) and (5, 60) Write the exponential equation whose graph contains these points.
y=km^x
so i substituted
10=k(m^2)   and
60=k(m^5)
im thinking m^2=10/k   and   m^5=60/k

and going forth like that

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lets just call it,  i, and get it over with

T33N_T1T4N

Member

Registered: 2007-02-10

Posts: 8

Re: exponential problem

following that way i got...
m=1.565
k=4.082

any one got a spellcheck for that ? lol

Last edited by T33N_T1T4N (2007-02-14 15:13:25)

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lets just call it,  i, and get it over with

gnitsuk

Member

Registered: 2006-02-09

Posts: 121

Re: exponential problem

This is the way to go:

We simultainiously need:

From the first equation we have:

and so substituting this into the second we have:

So substituting this value for m into the first equation gives:

So finally, substituting these values for k and m into the desired formula we get:

Check by substituting in (2,10) and (5,60) and you will find they satisfy this equation.

T33N_T1T4N

Member

Registered: 2007-02-10

Posts: 8

Re: exponential problem

ok i c now thank you

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lets just call it,  i, and get it over with