[试题]若|x+2|+y-3=0,则xy的值为( )。A. -8B. -6C. 5D. 6
X和Y满足, (Xgt 0,Ygt 0)=0.3 ,(xgt 0)=0.5 ,-|||-(Ygt 0)=0.4 ,-|||-则p(max(X,Y)>0 )= _
2.设随机变量(X,Y)的密度函数为 f(x,y)= ) A(e)^-2x-3y,xgt 0,ygt 0 0, = __
2.已知 dfrac (x)(x+y)=dfrac (1)(3) ,求 dfrac ({x)^2-(y)^2}(2xy+{y)^2} 的值.
6.已知A(0,3)和 (3,dfrac (3)(2)) 为椭圆 :dfrac ({x)^2}({a)^2}+dfrac ({y)^2}({b)^2}=1(ag
3.求极限lim_((x,y)to(0,0))(sin(xy))/(sqrt(4-xy)-2)=(0)/(0).3.求极限$\lim_{(x,y)\to(0,0
3.设 Xgeqslant 0,Ygeqslant 0 =dfrac (1)(5) Xgeqslant 0 =P Ygeqslant 0 =dfrac (2
[单选题]已知x-y=1,则x3-3xy-y3的值为( )。A.1B.2C.3D.5
lim _(xarrow y)dfrac (1-xy)({x)^2+(y)^2}-|||-bigcirc (3) lim 1-√(xy+1)-|||-y)→(0
3.已知 (int )_(0)^2f(x)dx=3 ,则 (int )_(0)^2[ f(x)+6] dx= __ 一