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September 6th, 2012, 12:51 PM  #1 
Newbie Joined: Sep 2012 Posts: 4 Thanks: 0  Alg help, multi variable
I got a couple multi variable equations I'm stuck on, I can't figure out what I'm doing wrong. One of them that's not multi variable is 19t (2(t1)/19) = 20 solve for T, I got 382/359 but it comes out to equal 20.2 something. Another one is u(v+w(v4)=z(v1), help please.

September 6th, 2012, 12:56 PM  #2 
Senior Member Joined: Feb 2012 Posts: 628 Thanks: 1  Re: Alg help, multi variable
For the second equation, assuming u, w, and z are constants, then we simply solve for v: There are infinitely many solutions in all four variables: just pick values for u, w, and z such that and then calculate the value for v using the above equation. 
September 6th, 2012, 12:59 PM  #3 
Global Moderator Joined: May 2007 Posts: 6,785 Thanks: 707  Re: Alg help, multi variable
Show your work for the first problem.

September 6th, 2012, 01:03 PM  #4 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs  Re: Alg help, multi variable
For the first problem: Multiply through by 19: For the second problem, there will not necessarily be a unique solution, you may solve for one variable in terms of the other three. 
September 6th, 2012, 01:15 PM  #5  
Global Moderator Joined: May 2007 Posts: 6,785 Thanks: 707  Re: Alg help, multi variable Quote:
 
September 6th, 2012, 01:57 PM  #6 
Newbie Joined: Sep 2012 Posts: 4 Thanks: 0  Re: Alg help, multi variable
I typed the wrong problem, it was v+8, but I redid the problem exactly as you showed and my online homework thing said it was wrong. I double checked it and everything, I'll have to ask the teacher tomorrow. I got one more problem that I want to make sure I got right, Atb/cb(15t) = 9 atb/cb+5bt=9 AtB= 9(cb+5tb) AtB=9c9b+45Bt At45Bt=9c8B t(A45B)=9c8B t=9C8B/A45B Is that correct? 
September 7th, 2012, 12:42 PM  #7 
Global Moderator Joined: May 2007 Posts: 6,785 Thanks: 707  Re: Alg help, multi variable
Be careful with using paraentheses. For example the last line should read t=(9C8B)/(A45B). Without the parentheses it looks wrong. Going from the first to the second line looks like also missing parentheses. 

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