![](https://lstatic.shangxueba.com/jiandati/h5/images/m_q_title.png)
A.("x)(P(x)∨Q(x)),P(x):x=1,Q(x):x=2,论域:{1,2}
B.($x)(P(x)∧Q(x)),P(x):x=1,Q(x):x=2,论域: {1,2}
C.($x)(P(x) →Q(x)),P(x):x>2,Q(x):x=0,论域:{3,4}
D.("x)(P(x)→Q(x)),P(x):x>2,Q(x):x=0,论域:{3,4}
A.("x)(P(x)∨Q(x)),P(x):x=1,Q(x):x=2,论域:{1,2}
B.($x)(P(x)∧Q(x)),P(x):x=1,Q(x):x=2,论域: {1,2}
C.($x)(P(x) →Q(x)),P(x):x>2,Q(x):x=0,论域:{3,4}
D.("x)(P(x)→Q(x)),P(x):x>2,Q(x):x=0,论域:{3,4}
判断下列子句集中哪些是不可满足的: (1)S={~P∨Q,~Q,P,~P} (2)S={P∨Q,~P∨Q,P∨~Q,~P∨~Q} (3)S={P(y)∨Q(y),~P(f(x))∨R(a)} (4)S={~P(x)∨Q(x),~P(y)∨R(y),P(a),S(a),~S(z)∨~R(z)} (5)S={~P(x)∨~Q(y)∨~L(x,y),P(a),~R(z)∨L(a,z),R(b),Q(b)} (6)S={~P(x)∨Q(f(x),a),~P(h(y))∨Q(f(h(y)),a)∨~P(x)} (7)S={P(x)∨Q(z)∨R(x),~P(y)∨R(y),~Q(a),~R(b)} (8)S={P(x)∨Q(z),~Q(y)∨R(y),~P(z)∨Q(z),~R(u)}
设P={x|x2—4x+3<0},Q={x|x(x-1)>2},则P∩Q等于()
A.{x|x>3}
B.{x|-1<x<2}
C.{x|2<x<3}
D.{x|1<x<2}
已知sin2x,cos2x是方程y"+p(x)y'+q(x)y=0的解,证明:
(1)sin2x,cos2x构成基本解组;
(2)1,cos2x也是基本解组; (3)求p(x),q(x).
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