130

131

> = ∑

= ×

= ∑

= ×

= ×

=

= × ( )

= × ( )

=

132

)

)

= × ∑ ∑ + × ( ) −

+ ×

∑ ∑

σ =

σ =

σ =.

133

134

135

136

137

138

139