【简答题】若(x+t)(x+6)的积中不含x的一次项,则t的值为______.
【简答题】He always to work by bike when he was in Shanghai. (go)
【简答题】He always ( go ) to work by car.
【简答题】Every morning Jim goes to work by train. He has a long way go to. So he always buys a newspaper. It helps Jim to spend(度过) the time on the train. Jim likes sport very much. One morning on the train he...
【单选题】He always go to school by ()bus.
【单选题】He is very ____________. He always go to work on time.
【简答题】--How he ( go ) to work? --He always ( go ) to work by car.
【简答题】设{X(t),t∈[0,+∞)}为正态过程,令Y(t)=X(t+1)-X(t),试证:{Y(t),t∈[0,+∞)}为正态过程。
【简答题】证明,若对于函数f(x)(-∞<x<+∞),等式f(x+T)=kf(x)成立,k与T为正数,则f(x)=a x φ(x),a为正常数,φ(x)是以T为周期的周期函数
【简答题】已知x(t)为矩形脉冲信号,求y(t)=x(t)*x(t)的傅里叶变换。