6
2 2! = 1*2 = 2 ;
3!*2!*10=6*2*10=120 .
240 .
4) 5 (240+240+240 =720) .
: 720 .
14.
) {1,2,3}×{a,b},
) {x,y}×{x,y,z},
) ×{a,b}.
:
)
1
={1,2,3};
2
={a,b},
1
2
= {1,2,3}×{a,b}= {(1,), (1,b), (2,a), (2,b), (3,a), (3,b)}
)
1
={x,y},
2
={x,y,z},
1
2
={x,y}×{x,y,z}= {(x,x), (x,y), (x,z), (y,x), (y,y), (y,z)}
)
1
=,
2
={a,b}
1
2
=.×{a,b}=
15. R = {(x,y)| x+y=x
2
–y
2
}, {1,2,-
1,0,7,8,9}.
:
x y
x+y=x
2
–y
2
2 1
-1 1
1 -1
0 -1
1 0
0 0
8 7
9 8
: (2,1); (-1,1); (1,-1); (0,-1); (1,0); (0,0); (8,7); (9,8).
16. {(1,2),(2,3),(1,3)}.
:
R={(1,2),(2,3),(1,3)} . ,
.
()
:
R
={(1,2),(2,3),(1,3),(1,1),(2,2),(3,3)}
: R={(1,2),(2,3),(1,3),(1,1),(2,2),(3,3)}
17. {(1,2),(2,3),(1,3)}.
:
R={(1,2),(2,3),(1,3)} . ,
.
, :
R
s
={(1,2),(2,3),(1,3),(2,1),(3,2),(3,1)}
: R
s
={(1,2),(2,3),(1,3),(2,1),(3,2),(3,1)}
18. {(a,b),(d,c),(c,b),(b,c)}.