A. S = {¬P(x,y)∨Q(x,y)}
B. S = {¬P(x,y)Q(x,y)}
C. S = {P(x,y) ꓦ Q(x,y)}
D. S = {P(x,y)Q(x,y)}
【单选题】谓词公式 x(P(x)∨ yR(y))→Q(x)中量词 x的辖域是()。A. x(P(x)∨ yR(y))B. P(x)C. (P(x)∨ yR(y)
谓词公式forall x)(P(x)arrow R(x,y))cap Q(x,y)可换名为forall x)(P(x)arrow R(x,y))cap Q(x,
【单选题】P(x, f(A))∨Q(x)和 ¬Q(f(y))∨R(z)的消解式为A. P(x,f(A))∨R(z)B. P(x,f(A))∨Q(x)∨R(z),
5.(单选题) 设f(x,y)=(x+y)/(xy),则f(x+y,x-y)=()A. $\frac{2x}{y^{2}-x^{2}}$B. $\frac{2x
公式(forall x)[ P(x)在Q(x,A)arrow (exists y)[ R(x,y)cup S(y)] ] 中,(forall x)[ P(x)
[单选题]已知集合P={x|0 ≤x ≤5,x∈Z},Q={y|y=|x2-1|,x∈P},则P∩Q中元素的个数是( ).(A)3.(B)6.(C)8.(D)9.
[单选题]已知y1(x)与y2(x)是方程y″+P(x)y′+Q(x)y=0的两个线性无关的特解,Y1(x)和Y2(x)分别是是方程y″+P(x)y′+Q(x)y=R1(x)和y″+P(x)y′+Q(x)y=R2(x)的特解。那么方程y″+P(x)y′+Q(x)y=R1(x)+R2(x)的通解应是:()A . c1y1+c2y2B . c1Y1(x)+c2Y2(x)C . c1y1+c2y2+Y1(x)D . c1y1+c2y2+Y1(x)+Y2(x)
单选题 已知y^(n-2)=3x^3-4x+1,则y^(n)|_(x=2)=().A. 9B. 17C. 32D. 36
【单选题】若 f (z)= u (x,y)+i v (x,y)在Z平面上解析, u (x,y)=x 2 -y 2 +x,则 v (x,y)=A. xy+xB.
5.(单选题) 设 z = varphi(x + y) + psi(x - y), 则必有()A. $z_{xx}^{\prime\prime} + z_{yy