f(t)的波形如图所示, 则F(s)=_____。1 ---|||-t-|||-(}^2[ dfrac {1)(2)-dfrac (1)(2)(e)^-2s-s(e)^-2s] 1 2

已知 F(s)= (e^-s)/(s(2s+1))，则 f(t)= ()A. $[1-e^{-(t-1)/2}]u(t)$B. $[1-e^{-(t-1)/2}

dfrac (1)(2)(S)_(8)^2-+(e)^-arrow (S)_(4)^2- (Na)^++dfrac (x)(4)(S)_(4)^2-+2(1-d

13.一平面简谐波t=0 s的波形如图，质元振幅为2cm，周期为2s，u=-2 m/s，=(dfrac (2)(3))m处的振动方程为( )=(dfrac

已知象函数 F(s)= (s+1)/(s(s+2))，则原函数 f(t)= L^-1(F(s)) 为 ()。A. $\frac{1}{2} + \frac{1}

f(x)= ({e)^4-dfrac (1)(3))-|||-dfrac (1)(2)(e)^4-|||-dfrac (1)(2)((e)^2-dfrac

脱吸因数法（平衡线为直线）：_(OG)=dfrac (1)(1-S)ln [ (1-S)dfrac ({Y)_(1)-({X)_(2)}^3}({Y)_(2)-

dfrac ({Q)_(1)-(Q)_(2)}(2S)-|||-B Q1-Q2 ,-|||-Q1-Q2

2-15 已知 _(1)(t)=u(t+1)-u(t-1) _(2)(t)=8(t+5)+8(t-5) _(3)(t)=-|||-(t+dfrac (1)(2)

=dfrac (1)(2)(t)^2+3t-4-|||-式中t的单位为s x,y的单位为m。-|||-(1)以时间t为变量,写出质点位置矢量的表达式;-|||-

_(1)-(F)_(2)-|||-C. dfrac (2)(3)(F)_(1)+dfrac (1)(3)(F)_(2)-|||-D. dfrac (2)(3)(