a |
a+b+c |
b |
b+c+d |
c |
a+c+d |
d |
d+a+b |
A.0<S<1 | B.1<S<2 | C.2<S<3 | D.3<S<4 |
a |
a+b+c |
b |
b+c+d |
c |
a+c+d |
d |
d+a+b |
a |
a+b+c+d |
b |
a+b+c+d |
c |
a+b+c+d |
d |
a+b+c+d |
a |
a+b+c |
b |
b+c+d |
c |
a+c+d |
d |
d+a+b |
a+d |
a+b+c+d |
a+b |
a+b+c+d |
c+b |
a+b+c+d |
c+d |
a+b+c+d |
a+b+c+d |
a+b+c+d |
|
A.{(0,3),(1,2)} | B.{0,1} | C.{3,2} | D.{y丨y≤3} |
A.[
| B.[
| C.[1,
| D.[3,
|
x-b |
x+2 |