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Mathematical investigations in the theory of value and prices / by Irving Fisher
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in the theory of value and prices. 59

dTJ

c*U

dTJ

dTJ 1

<*A,r

dTJ

dBdTJ

' dU,dTJ

*A«..

rfl)

'

dTJ

-rfM.,,-

(2 m 1) nindepen-^ dent

equations,no new

^A ff , 2

dR, i

dA nt

d Bk, 2

'iMr

dTJ

dTJ

dTJ

dTJ

dTJ

dK.:

d^.n

dA K ,n

dB^,'

' <*M. -

unknowns.

~Pa

p b

Pm

+ Pa

+ Pt

+ Pm

No. equations: m + (n 1) +2mn+ (2m 1) n=.4mn + m lNo. unknowns: 2mn + m + 2mn + 0 =4 mn-\-m.

There are just one too few equations. It may not be evident atfirst why the second set does not contain n independent equationsinstead of ( n1). The point is that any one of these equations canbe derived from the others together with the equations' of the firstset. Thus multiply the equations of the first set by p p b , . . . p mrespectively and add the resulting equations arranging as follows :

A*, \ Pa + B., 1 Pb + 4- M w> i . p m +

+ A,,, 2 Pa + s Pb + + 5 . p m -t- ^ _

+ . - . - .

I - A,,, " Pa "4" B wjn . p b -j- 4 . p m

( + p m +

J + A <,»'I ) «4B,.^ + . . 4- ! /'m 4

+ A. >n Pa + B . p b + . . . + M K|n . 2^*1

Subtracting from this equation the sum of all but the first (say)of the second set, our result is :

A w , i Pa 4- B t Pb 4~ -4 , . p m =

A 1 Pa + B,, . Pi, 4- + , . p m

which is the first equation of the second set. This equation is there-fore dependent on the others, or there is one less independent equa-tion than appears at first glance. Hence we need one more equa-tion. We may let:

Pa-= 1.

This makes A the standard of value (of. §5).

No such limitation applies to the equations in Chapter IV.