Polynomial Division puzzler(well to me anyway :P )

[ramstin]

O.K I factored and reduced an equation I am doing down to (s+5t)/(t-s)

I could not figure it out so I went to webmath and used a calculator to find out the answer so I could reverse solve the problem. The answer is 1 according to webmath. Any hints on how to get started on this becuase I do not see how you can get rid of the 5?:yuck:

 

[Plastic Photon]

O.K I factored and reduced an equation I am doing down to (s+5t)/(t-s)

I could not figure it out so I went to webmath and used a calculator to find out the answer so I could reverse solve the problem. The answer is 1 according to webmath. Any hints on how to get started on this becuase I do not see how you can get rid of the 5?:yuck:

If it is an equation, what is the remaining part of the equation? How did you factor what you have so far?

 

[Hurkyl]

There's a very easy way to prove (s + 5t) / (t - s) is not identically equal to 1. (I'll give you time to figure this one out -- and I advise doing so, it's a widely useful but overlooked technique)


Have you tried going through the problem a second time? I find that I rarely make the same mistake twice. So when I'm not completely confident in my arithmetic, I will often do the same problem twice from scratch (and in different ways, if possible) to check myself. If I get a mismatch, I can often track down exactly what I did wrong.


But finally, I can't possibly figure out what you've done wrong unless you showed your work.

 

[ramstin]

O.k. Here goes. The equation is
20s^2+9st+t^2 2s^2-7st+3t^2 5s^2+6st+t^2
-------------- * --------------- * --------------
5s^2-14st-3t^2 t^2+3st-4s^2 10s^2-3st-t^2


factored out to

(5s+t)(4s+t) (2s-t)(s-3t) (5s+t)(s+5t)
------------*-----------*-------------
(5s+t)(s-3t) (t-s)(t+4s) (5s+t)(2s-t)

reduced to
(s+5t)/(t-s)
from this point I am stuck.

 

[assyrian_77]

The numerator in your last fraction: $5s^2+6st+t^2\neq(5s+t)(s+5t)$.

 

[ramstin]

I re did the equation and ended up with (s+t)/(s-t). Thanks everyone.

 

[HallsofIvy]

So far you haven't shown us any equation. An equation has to have a "= " somewhere in it!

And (s+t)/(s-t) still isn't equal to 1!

 

[ramstin]

Sorry It was perform the indicated operation. Not solve the equation. Honestly i did not know an equation had to have a = . The instructor at the community college I am going to never spent any time on terms.

 

[ramstin]

As for the 1 thing. I think the calculator on webmath is messed up. It said (s+t)/(s-t) =1 But my calculator says in doing so you would have to divide by zero which cannot be done.