My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum


Reply
 
LinkBack Thread Tools Display Modes
December 12th, 2012, 05:34 PM   #1
Newbie
 
Joined: Dec 2012

Posts: 2
Thanks: 0

solution for a^x + bx - c =0

Please help me find a solution for x in following equation a^x + bx - c =0, where a, b, c are some arbitrary constant and x is a variable. If a=1.07, b = 3.774 x 10^-3 and c = 1.5589, then x =6.5 satisfies the equation. However, I am finding it difficult to find a method for solving the equation other than from hit and trial.
Thanks in advance.
niraj is offline  
 
December 12th, 2012, 07:09 PM   #2
Math Team
 
Joined: Oct 2011
From: Ottawa Ontario, Canada

Posts: 13,282
Thanks: 931

Re: solution for a^x + bx - c =0

Quote:
Originally Posted by niraj
Please help me find a solution for x in following equation a^x + bx - c =0, where a, b, c are some arbitrary constant and x is a variable. If a=1.07, b = 3.774 x 10^-3 and c = 1.5589, then x =6.5 satisfies the equation. However, I am finding it difficult to find a method for solving the equation other than from hit and trial.
Thanks in advance.
a^x + bx - c = 0 : cannot be solved directly; numeric method required (or hit and miss!)...

You show: b = 3.774 x 10^-3 ; what does that mean? is "x" a multiplication symbol?
If so, start using * as multiplication symbol.
Denis is offline  
December 12th, 2012, 07:14 PM   #3
Senior Member
 
MarkFL's Avatar
 
Joined: Jul 2010
From: St. Augustine, FL., U.S.A.'s oldest city

Posts: 12,204
Thanks: 511

Math Focus: Calculus/ODEs
Re: solution for a^x + bx - c =0

is also preferred over x, or as well. (However, the asterisk is easiest to use since the others are not on the standard keyboard.)
MarkFL is offline  
December 13th, 2012, 09:49 PM   #4
Newbie
 
Joined: Dec 2012

Posts: 2
Thanks: 0

Re: solution for a^x + bx - c =0

Thanks for your help.
Yes 'x' is not variable in b = 3.774 x 10^-3. I should have used * sign instead. Thanks for your suggestion Denis, MarkFL.
niraj is offline  
December 14th, 2012, 06:01 AM   #5
Global Moderator
 
Joined: Dec 2006

Posts: 19,701
Thanks: 1804

Expressing x explicitly in terms of a, b and c requires a special function called the Lambert W function.
skipjack is online now  
December 14th, 2012, 07:27 AM   #6
Math Team
 
Joined: Oct 2011
From: Ottawa Ontario, Canada

Posts: 13,282
Thanks: 931

Re: solution for a^x + bx - c =0

How is your 6.5 arrived at ? I make it ~19/3 (quite close to 6 1/3)

1.07^(19/3) + 3.774*10^(-3)*(19/3) - 1.5589 = .0000373...
Denis is offline  
Reply

  My Math Forum > High School Math Forum > Algebra

Tags
solution



Search tags for this page
Click on a term to search for related topics.
Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Why my solution is different from sample solution? rain Real Analysis 1 July 17th, 2013 12:28 PM
my correct solution but another solution? davedave Calculus 1 January 31st, 2012 02:48 PM
Need solution of following eqn. bdcrown007 Calculus 1 January 26th, 2011 07:27 PM
trying to make a solution (liquid solution...) problem... TreeTruffle Algebra 2 March 27th, 2010 01:22 AM
help with a no solution leith00000 Algebra 2 August 7th, 2009 12:15 PM





Copyright © 2018 My Math Forum. All rights reserved.