Solving exponenial equations using matrices?

[Manan]

Not sure if its possible to solve exponential equations using matrices but if there is a different method then please help or suggest...

The equation is modeled as: E(x)=p10^(qx-1) - m, p,q,m are all real constants

Q. State three suitable exponential equations that will give the following values: p=38.00, q=-0.35, m=0.7
Given information: E(3)=1/6, E(2)=7/12 and E(5/2)=1/3

[shadows]

From the looks at the given values.. Looks like a cas question.

Doesn't the question just ask you to state the 3 equations?


In that case just sub the given info... E(2) =1/6.. Etc.


And just state the 3 equations...

I've never encountered a question where I have used matrices with exponential questions...
But if you are good and matrices, and prefer to do it like that, then there's nothing stopping you!

[BubbleWrapMan]

There isn't a way of doing that with matrices (that I know of). It's a CAS question, after you've set up the equations.

[Alwin]

Not sure if its possible to solve exponential equations using matrices but if there is a different method then please help or suggest...

I have seen a method by hand, which involves firstly subtracting and dividing to get rid of constants and eventually find the values in terms of logs using simultaneous equations. If you were feeling adventurous, you could solve the simultaneous equations using matrix methods. However, since you're dealing with 3 variables it may be more complex. If you're interested in solving by hand, I can post it later.

Otherwise, consider the the question you have posted . If you had been able to set up matrices to solve, do you know (in the methods course) how to solve a 3x3 by hand? No. So its a CAS question, which basically you can do anything you want on cas so long as you write down the right answer. Do what Timmeh suggests, set up the equations and solve, no need to muck around with matrices

[Manan]

Not really sure how to do it on cas.  
I tried the simultaneous method(linsolve) and didn't work so don't know how to approach it..

[Alwin]

Not really sure how to do it on cas.  
I tried the simultaneous method(linsolve) and didn't work so don't know how to approach it..

Q. State three suitable exponential equations that will give the following values: p=38.00, q=-0.35, m=0.7
Given information: E(2)=1/6, E(2)=7/12 and E(5/2)=1/3

Did you make a typo?? why do you have E(2) twice..

[shadows]

Not really sure how to do it on cas.  
I tried the simultaneous method(linsolve) and didn't work so don't know how to approach it..

What cas are you using?

Play around more with your calculator. It's really important you become familiar with it..

[BubbleWrapMan]

You should be able to use the normal solve function, except you write all three equations separated by ' and '.

e.g. solve(x=y and 2x=z and 3x+z=y,x)

[Manan]

You should be able to use the normal solve function, except you write all three equations separated by ' and '.

e.g. solve(x=y and 2x=z and 3x+z=y,x)

Thanks you so much Timmeh, I didn't know that i could solve 3 equation by adding 'and' in the solve function. I thought it was only applicable for 2 equations.

[Alwin]

The equation is modeled as: E(x)=p10^(qx-1) - m, p,q,m are all real constants

Q. State three suitable exponential equations that will give the following values: p=38.00, q=-0.35, m=0.7
Given information: E(2)=1/6, E(2)=7/12 and E(5/2)=1/3

QUESTION: are you sure what you gave us is correct??

I raised this before about the E(2) appearing twice. So, I decided to check it by graphing E(x)=38.00 10^(-0.35x-1) - 0.7

E(2) = 0.0581997... approx 7/12 NOT 1/6 in the first equation
E(5/2) = -0.642485... not even close to 1/3... o.O

maybe perhaps double check the question in case that's the problem

[Manan]

QUESTION: are you sure what you gave us is correct??

I raised this before about the E(2) appearing twice. So, I decided to check it by graphing E(x)=38.00 10^(-0.35x-1) - 0.7

E(2) = 0.0581997... approx 7/12 NOT 1/6 in the first equation
E(5/2) = -0.642485... not even close to 1/3... o.O

maybe perhaps double check the question in case that's the problem

Sorry guys...just a typo. E(3)=1/6