6.3 The Dale Equation 247
Note that the theorem cannot be applied toAdirectly sinceφmdoes not
satisfy the Appell equation for anyF(x).
Using the identity
|t
i+j− 2
aij|n=t
n(n−1)
|aij|n,
it is found that
P=(1+x)
−n
2
A,
P 11 =(1+x)
−n
2
+1
A 11. (6.3.4)
Hence,
(1 +x)A
′
=n
2
A−(c−1)A 11. (6.3.5)
Let
αi=
∑
r
x
r− 1
A
ri
, (6.3.6)
βi=
∑
r
(−1)
r
A
ri
, (6.3.7)
λ=
∑
r
(−1)
r
αr
=
∑
r
∑
s
(−1)
r
x
s− 1
A
rs
=
∑
s
x
s− 1
βs, (6.3.8)
whererands=1, 2 , 3 ,...,nin all sums.
Applying double-sum identity (D) in Section 3.4 withfr=randgs=
s−1, then (B),
(i+j−1)A
ij
=
∑
r
∑
s
[x
r+s− 1
+(−1)
r+s
c]A
ri
A
sj
=xαiαj+cβiβj (6.3.9)
(A
ij
)
′
=−
∑
r
∑
s
x
i+j− 2
A
is
A
rj
=−αiαj. (6.3.10)
Hence,
x(A
ij
)
′
+(i+j−1)A
ij
=cβiβj,
(x
i+j− 1
A
ij
)
′
=c(x
i− 1
βi)(x
j− 1
βj).
In particular,
(A
11
)
′
=−α
2
1 ,
(xA
11
)
′
=cβ
2
1