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Javascript Algebra solver

Posted by David Wees on Nov 9, 2006

So I created an algebra solver, I've done some more work on it recently that allows users to enter a much wider variety of equations into the boxes, and I've also discovered that it will quite happily solve the single variable case (with 1 equation), making it more useful than I originally intended. It will now also solve many quadratic equations as well, with some additional functionality I added today.

You can enter systems of equations such as:

2(a-2)+3a+3=13
2b+2+a=13

or

2(a-4)+(b+2c)+d=3(d-4)-3(a+2)+23
2a+(2b+4c)/2+3d/2=10/4
a+3b+c+d=20
a-b+c-d=10

etc... into the textarea, and it should solve all of these quite happily.

It will also solve quadratic equations such as:

x^2-6x+5=0

or the more complicated

2x^2-3(x-4)+3/4x-2x+(x-2)(2x+1)=3x^2-16

Please let me know if you spot any errors in the program.

Check it out here.

Comments

Comment by Luis (not verified) posted on Dec 26, 2006
1/(x-3)=1 does not work

Comment by Macy (not verified) posted on Jan 2, 2007
I couldn't get (2+3i)(1-4i) to work

Comment by David Wees posted on Jan 7, 2007
Hey Luis: My algebra solver will not handle rational expressions unfortunately, but with some work I could have it handle simple expressions of the sort you tried. You'd have to multiply the denominator of the LHS over to the RHS. Macy: You need to set the expression equal to something to make it an equation. Try (2+3i)(1-4i) = 0. That seems to work.

Comment by Teal Nero (not verified) posted on Jan 29, 2007
This thing was a life saver! Thanks so much for this. Now I can get some sleep..

Comment by Vic (not verified) posted on Mar 22, 2007
I can't make xy-5-x-y=0 work.

Comment by David Wees posted on Mar 26, 2007
xy-5-x-y=0 has two reasons why it won't work. First it has 2 variables and 1 equation so it does not have a unique solution. Second, it involves a quadratic term with mixed variables which my solver cannot handle. Dave

Comment by Grace Levine (not verified) posted on Jul 12, 2007
I cannot do simple radicals such as √49x^10?

Comment by David Wees posted on Jul 25, 2007
That's true. Parsing a radical is not too difficult to do but as this is my hobby, and I'm not being paid to do it, I haven't bothered adding the code. Basically, although my solver handles tonnes of cases, there are some that aren't worth the extra coding. For instance, it doesn't solve cubic equations either, even though there is a (relatively) straight forward procedure for doing so.

Comment by Tyler (not verified) posted on Sep 5, 2007
Tyler: I cannot get f(x)=2x^2+x-7 to work. Nor could i get r^2-5r-6/(r+1). I tried putting in =0 at the end but it came up with r1=0 and r2=0.

Comment by David Wees posted on Sep 5, 2007
Hi Tyler: Yeah my solver won't handle rational expressions properly as its not that advanced. Also, your first expression isn't technically an equation, so it can't solve it either. Try: 0 = 2x^2 + x - 7 instead.
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