A.{ t | tÎR Ú tÎS } 、{ t | tÎR Ù tÏS } 、{ t | tÎR Ù tÎS }
B.{ t | tÎRÙ tÎS } 、{ t | tÎR Ù tÏS } 、{ t | tÎR ÚtÎS }
C.{ t | tÎR Ú tÏS } 、{ t | tÎR Ù tÎS } 、{ t | tÎR Ù tÏS }
D.{ t | tÎR ÚtÏS } 、{ t | tÎR Ù tÎS } 、{ t | tÎR Ú tÎS }
A.{ t | tÎR Ú tÎS } 、{ t | tÎR Ù tÏS } 、{ t | tÎR Ù tÎS }
B.{ t | tÎRÙ tÎS } 、{ t | tÎR Ù tÏS } 、{ t | tÎR ÚtÎS }
C.{ t | tÎR Ú tÏS } 、{ t | tÎR Ù tÎS } 、{ t | tÎR Ù tÏS }
D.{ t | tÎR ÚtÏS } 、{ t | tÎR Ù tÎS } 、{ t | tÎR Ú tÎS }
A.DSolve[{x'[t]+y[t]==Cos[t],y'[t]+x[t]==Sin[t]},{x[t],y[t]},t]
B.DSolve[x'[t]+y[t]=Cos[t],y'[t]+x[t]=Sin[t],{x[t],y[t]},t]
C.DSolve[{x'[t]+y[t]==Cos[t],y'[t]+x[t]==Sin[t]},x[t],y[t],t]
D.DSolve[{x'[t]+y[t]==Cos[t],y'[t]+x[t]==Sin[t]},{x,y},t]
A.DSolve[{x'[t]+y[t]==Cos[t],y'[t]+x[t]==Sin[t]},{x[t],y[t]},t]
B.DSolve[x'[t]+y[t]=Cos[t],y'[t]+x[t]=Sin[t],{x[t],y[t]},t]
C.DSolve[{x'[t]+y[t]==Cos[t],y'[t]+x[t]==Sin[t]},x[t],y[t],t]
D.DSolve[{x'[t]+y[t]==Cos[t],y'[t]+x[t]==Sin[t]},{x,y},t]
设{X(t),t∈T}与{Y(t),t∈T}为相互独立的实平稳过程,且E[X(t)]=mX,E[Y(t)]=mY。令Z(t)=X(t)Y(t),t∈T。
证明下列各式. (1)f1(t)*f2(t)=f2(t)*f1(t); (2)f1(t)*[f2(t)*f3(t)]=f3(t)*[f1(t)*f2(t)]; (3)a[f1(t)*f2(t)]=[af1(t)]*f2(t)=f1(t)*[af2(t)](a为常数); (4)eat[f1(t)*f2(t)]=[eatf1(t)]*[eatf2(t)](a为常数); (5)[f1(t)+f2(t)]*[g1(t)+g2(t)]=f1(t)*g1(f)+f2(t)*g1(t)+f1(t)*g2(t)+f2(t)*g2(t);
(7)f(t)*δ(t)=f(t); (8)f(t)*δ(t—t0)=f(t—t0); (9)f(t)*δ’(t)=f’(t);
A.syms t; G=simplify(diff(t^2*sin(t),t,3))
B.syms t; G=simplify(int(t^2*sin(t),t,3))
C.syms t; G=simplify(diff(t^2*sin(t),t))
D.syms t; G=simplify(int(t^2*sin(t),t))
A.don’t ; doesn’t
B.doesn’t ; don’t
C.don’t ; don’t
D.doesn’t ; doesn’t
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