That product that you bought at the lower price is ______ the one that we sell at a slight
A.inferior to
B.more inferior than
C.inferior to
D.inferior than
A.inferior to
B.more inferior than
C.inferior to
D.inferior than
设f(x,y)与ψ(x,y)均为可微函数,且ψˊy(x,y)≠0,已知(xo,yo)是f(x,y)在约束条件ψ(x,y)=0下的一个极值点,下列选项正确的是()
A.若fˊx(xo,yo)=0则fˊy(xo,yo)=0
B.若fˊx(xo,yo)=0则fˊy(xo,yo)=0
C.若fˊx(xo,yo)≠0则fˊy(xo,yo)≠0
D.若fˊx(xo,yo)≠0则fˊy(xo,yo)≠0
如果点P(x,y)以不同的方式趋于Po(xo,yo)时,f(x,y)趋于不同的常数,则函数f(x,y)在po(xo,yo)处的二重极限____________. (2)函数f(x,y)在点(xo,yo)连续是函数在该点处可微分的___________条件,是函数在该点处可偏导的__________条件. (A)充分而不必要 (B)必要而不充分 (C)必要且充分 (D)既不必要又不充分 (3)函数f(x,y)的二阶偏导数fxy与fyx在区域D内相等的充分条件____________. (A)连续但不可偏导 (B)可偏导但不连续 (C)连续且可偏导但不可微分(D)可微分
(5)若函数F(x,y)是C(1)类函数,满足F(xo,yo)=0且Fu(xo,yo)_________,则方程F(x,y)=0在点(xo,yo)的某邻域内可确定C(1)类函数y=y(x). (6)gradf(xo,yo)的方向是函数f(x.y)在点(xo,yo)处取得__________的方向;gradf(xo,yoo)是等量线f(x,y)=f(xo,yo)上点(xo,yo)处的___________向量并指向等量线的高值方向.
A.take a shower
B.sighing
C.framework
D.disable person
大接地电流系统中,为什么Yo/△-11接线的变压器差动保护,Y侧电流互感器的二次绕组必须接成三角形?