【单选题】设y1与y2是二阶线性非齐次方程 的任意两个线性无关的特解,则对应的齐次方程 的解为( )
【单选题】设对称振子总长度为2l,下列关于有效长度的计算正确的是【】
【单选题】AMERICA'S central bank sent a clear message this week. For the second consecutive meeting, the Federal Open Market Committee, the central bank's policy-making committee, left short term interest rates...
A.
interpret the message from the central bank,
B.
justify the rise of short term interest rates.
C.
illustrate what is weakness and undue growth.
D.
contrast different views on economic indices.
【单选题】设y1、y2是二阶常系数线性齐次方程y'+p1y'+p2y=0的两个特解,C1、C2为两个任意常数,则下列命题中正确的是
【单选题】The word 'message' in the last paragraph means
【单选题】设f1(χ)和f1(χ)为二阶常系数线性齐次微分方程y〞+py′=0的两个特解若由f1(χ)和f1(χ)能构成该方程的通解,下列哪个方程是其充分条件?
A.
f1(χ)·f′2(χ)- f2(χ) f′1(χ)=0
B.
f1(χ)·f′2(χ)- f2(χ) f′1(χ)≠0
C.
f1(χ)f′2(χ)+ f2(χ) ·f′1(χ)=0
D.
f1(χ)f′2(χ)+f2(χ) f′1(χ)≠0
【单选题】设对称振子总长度为 2 l ,下列关于有效长度的计算正确的是【】。
【单选题】America's central bank sent a clear message this week. For the second consecutive meeting, the Federal Open Market Committee, the central bank's policy-making committee, left short-term interest rates...
A.
strongly believed in economic recovery.
B.
took for granted economic expansion.
C.
were cautious in their excessive investment.
D.
had doubts about the effects of price pressure.