[8y / (3y+9)]+[(7y-13) / (2y+6)]= [(7y-4) / (y+3)]
solve for y

my roommate cant figure it out and im stupid with math; help!

9/21/2006 11:11:47 PM

multiply both sides by (y+3).

pull the (y+3) out of the denominators on the left side. they cancel out what you just multiplied into the fraction.

this gives you a bunch of y's with simple numbers in front of um.

solve like normal algebra problem.


got bored and did it:
meets at y=-3, but thats undefined on both sides obviously. if you simplify the equations though, you dont have this problem. unless there is some calculus im just choosing to ignore, having not done anything in a long time (though i think simplification is perfectly allowable in order to find a solution).


[Edited on September 21, 2006 at 11:34 PM. Reason : .]

9/21/2006 11:18:52 PM

^ yep y = -3

comes up to something like this:

(8y/3) + [(7y-13)/2] = 7y -4 //got this by factoring (y+3) in the denominator then multiply both sides by (y+3)

16y + 21y -39 = 42y - 24

16y +21y -42y = -24 + 39

-5y = + 15 = > y = -3

9/21/2006 11:37:01 PM

Excel -> Solver.

Problem solve(r)d.

9/21/2006 11:46:34 PM

I didn't work the problem out, but just so it's clear; if y=-3 is the only "possible" solution you get from solving it algebraicly, then there's no solution. It doesn't matter if it's a solution after the original equation is "simplified"; if it's dividing by zero in the original equation, it's not a solution.

9/22/2006 4:47:43 AM

^correct

9/22/2006 5:04:32 AM