求微分方程[img=261x61]17da6536c0cca5d.png[/img]的通解； （ ）
A: C18*cos(t) - C20*sin(t) - C19*t*cos(t) - C21*t*sin(t)
B: C18*cos(t) + C20*sin(t) - C19*t*cos(t) - C21*t*sin(t)
C: C18*cos(t) + C20*sin(t) + C19*t*cos(t) + C21*t*sin(t)
D: -C18*cos(t) + C20*sin(t) + C19*t*cos(t) + C21*t*sin(t)
A: C18*cos(t) - C20*sin(t) - C19*t*cos(t) - C21*t*sin(t)
B: C18*cos(t) + C20*sin(t) - C19*t*cos(t) - C21*t*sin(t)
C: C18*cos(t) + C20*sin(t) + C19*t*cos(t) + C21*t*sin(t)
D: -C18*cos(t) + C20*sin(t) + C19*t*cos(t) + C21*t*sin(t)
举一反三
- 求微分方程[img=269x55]17da6536a9fba07.png[/img]的通解； （ ） A: (C15*sin(2*t))/exp(3*t) + (C16*sin(2*t))/exp(3*t) B: (C15*cos(2*t))/exp(3*t) - (C16*sin(2*t))/exp(3*t) C: (C15*cos(2*t))/exp(3*t) + (C16*cos(2*t))/exp(3*t) D: (C15*cos(2*t))/exp(3*t) + (C16*sin(2*t))/exp(3*t)
- 设\(z = {e^{x - 2y}}\)，而\(x = \sin t\)，\(y = {t^3}\)，则全导数\( { { dz} \over {dt}} = \) A: \({e^{\sin t - {t^3}}}(\cos t - 6{t^2})\) B: \({e^{\sin t - 2{t^3}}}(\sin t - 6{t^2})\) C: \({e^{\cos t - 2{t^3}}}(\cos t - 6{t^2})\) D: \({e^{\sin t - 2{t^3}}}(\cos t - 6{t^2})\)
- x=tan(t)sin(t)-cos(t)=?
- 求解常微分方程组<img src="http://img1.ph.126.net/B8qMozAYz7oEzmWV3LBSvg==/6597340246519736485.png" />, 应用的语句是? DSolve[{x'[t]+y[t]==Cos[t],y'[t]+x[t]==Sin[t]},{x,y},t]|DSolve[{x'[t]+y[t]==Cos[t],y'[t]+x[t]==Sin[t]},x[t],y[t],t]|DSolve[{x'[t]+y[t]==Cos[t],y'[t]+x[t]==Sin[t]},{x[t],y[t]},t]|DSolve[x'[t]+y[t]=Cos[t],y'[t]+x[t]=Sin[t],{x[t],y[t]},t]
- 下列函数是奇谐函数的是？ A: x(t)=sin(3t+2)+1 B: x(t)=cos(t+2) C: x(t)=sin(t)+2 D: x(t)=cos(2t+1)