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find x maths question
emsfactory - 18/3/16 at 07:20 PM

Hi all,

a chap in work is doing some maths and is stuck on this. I said I would have a look but I cannot remember how to do these. Maths was too many moons ago for me.

Anyone know how to do it or what type of problem it is so I can have a go.

Cheers,

y=((a+x)/(5-bx))

[Edited on 18/3/16 by emsfactory]

[Edited on 18/3/16 by emsfactory]


mark chandler - 18/3/16 at 07:31 PM

Looks like a quadratic equation, so easy I'll let someone else do it


cliftyhanger - 18/3/16 at 07:44 PM

y=((a+x)/(5-bx))
5y-ybx=a+x
5y-ybx-a=x
5y-a=x+ybx
5y-a=x(1+yb)
x=(5y-a)/(1+yb)

does that work? been a while (30 years...)


bi22le - 18/3/16 at 07:57 PM

I love a bit of algebra.

A quick scribble suggests
X = (5y-a) /(yb+1)

Damn too slow! Thats how i did it as well.

[Edited on 18/3/16 by bi22le]


emsfactory - 18/3/16 at 08:03 PM

Yeah thats where we got too. I am thinking there is more to it though. Some formula to be applied to make it nicer.


rash12 - 18/3/16 at 08:35 PM

would need y a and b values to.input.if he wants a numerical value of x


nero1701 - 18/3/16 at 09:00 PM

x=(5y-a)/(1+yb)

This is as far as you can take it unless you start with derivatives

then it becomes

(d)/(dx)((a+x)/(5-b x)) = (a b+5)/(b x-5)^2


jonrotheray - 18/3/16 at 09:55 PM

Presumably a and b are constants, x and y are variables.

You have too many unknowns to solve this equation, but:

when y = 0, x = -a
when x = 0, y= a/5

Given values for the constants a and b, you could then draw a graph of the equation - it's linear, so should be a straight line.


sprouts-car - 18/3/16 at 10:05 PM

quote:
Originally posted by jonrotheray
Presumably a and b are constants, x and y are variables.

You have too many unknowns to solve this equation, but:

when y = 0, x = -a
when x = 0, y= a/5

Given values for the constants a and b, you could then draw a graph of the equation - it's linear, so should be a straight line.


Its not linear


JacksAvon - 18/3/16 at 10:09 PM

pies are the answer,beef lamb,steak and kidney kidney,chicken..............................just pies


bi22le - 18/3/16 at 10:17 PM

Nope thats it. You cant simplify it.