解
(123) 3 2
=(1×3+2×2+3×1)=(10) 1 .
(3) 2 1
( 12); 3 解
2 4 1
2×( 1)2×23 ( 12)= 2 13××(( 11))13××2 = 12
2
36 .
(4) 2 1
3
11 1 114304 0 1 2 40
31 ; 2
31 2 1
解
1 114304 02
= 6 78 .
1 10
3 4
1 2
20 5 6 (5)(x a11a12a13 x1
1x2x3) a12a22a23 a x2 ;
13a23a33 x3 解
x a11a12a13 x(1
1x2x3) a a12a13a22a23a23 x2
33 x3 =(a11x1+a12x2+a13x3
a12x1+a22x2 x+a1
13x123x2+a33x3) x2
x 3
=a11x12+a22x22+a33x32
+2a12x1x2+2a13x1x3+2a23x2x3.
+a23x3
a