Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2006-10-17 21:56:08

Toast
Real Member
Registered: 2006-10-08
Posts: 1,321

Simultaneous Literal Equations



to


to
by subtraction
to

Correct?

According to the answers section, no. Can someone tell me where I went wrong?
I have a feeling the subtraction bit is wrong, can someone help me plz.

Offline

#2 2006-10-17 22:07:25

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: Simultaneous Literal Equations

Yes, you're right. You made a mistake when you did the subtraction.

You were meant to get ay-by = a-b.

Unfortunately, following that through gets you to y = (a-b)/(a-b), which is undefined. So either the problem is unsolvable, or you made another mistake somewhere else. I can't see any other mistakes though.

Edit: I just worked it through myself and got to the same place. So I'd say it's impossible. You could write y in another form, like 2-x, but you can't have it in terms of a and b.


Why did the vector cross the road?
It wanted to be normal.

Offline

#3 2006-10-17 22:29:19

Toast
Real Member
Registered: 2006-10-08
Posts: 1,321

Re: Simultaneous Literal Equations

Thanks mathsyperson
(woops)

Last edited by Toast (2006-10-18 01:07:43)

Offline

#4 2006-10-18 00:57:43

Dross
Member
Registered: 2006-08-24
Posts: 325

Re: Simultaneous Literal Equations

mathsyperson wrote:

Unfortunately, following that through gets you to y = (a-b)/(a-b), which is undefined.

(a-b)/(a-b) is only undefined for a = b... otherwise it's just 1.

If a = b, then the second to last line of the original post (with correction) becomes:

y(a-a)=a-a

y(0)=0.

Then y is a free variable. It can take any value, and x = 2 - y is a solution for any y.


Bad speling makes me [sic]

Offline

#5 2006-10-18 00:58:48

Dross
Member
Registered: 2006-08-24
Posts: 325

Re: Simultaneous Literal Equations

Toast wrote:

Thanks dross

Credit goes to mathsyperson, I'm afraid. Now you can thank me, though tongue


Bad speling makes me [sic]

Offline

#6 2006-10-18 01:08:37

Toast
Real Member
Registered: 2006-10-08
Posts: 1,321

Re: Simultaneous Literal Equations

lol sorry, i didn't look properly at who wrote the message

Offline

#7 2006-10-18 02:28:46

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: Simultaneous Literal Equations

Oh, silly me. Of course (a-b)/(a-b) = 1. I must have been in a hurry or something. Sorry!


Why did the vector cross the road?
It wanted to be normal.

Offline

Board footer

Powered by FluxBB