x+y=1/t 1.2x+y=10/9t x+0.75y=1/(t+2.5) 求解方程式,求t的值

x+y=1/t 1.2x+y=10/9t x+0.75y=1/(t+2.5) 求解方程式,求t的值 微分方程 矩阵 x'(t)=x(t)+y(t)+2t y'(t)=x(t)+y(t)-2t (x+y)t=(1.2x+y)·0.9t=(x+0.75y)(t+2.5),求t 10(8y-x)=6(12y-x)=t(14y-x)t是多少 （1.2X+Y）*0.9T=(X+0.75Y)(T+2.5),求解T等于多少? mathematica编程哪里错啦,急~~NDSolve[{y''[t] == -9.81, y[0] == 11, y'[0] == 0, x[t] = 1.5 t, WhenEvent[y[t] == 0, y'[t] -> -0.80 y'[t]], WhenEvent[y[t] == 0, x'[t] -> -0.80 x'[t]], WhenEvent[ Abs[y'[t]] < 1*10^(-6), {tf = Sqrt[x^2 + [T,Y]=ode45(@rigid,[0 1],[rand(15,1)]);plot(T,Y(:,1),'-',T,Y(:,2),'-.',T,Y(:,3),'.',T,Y(:,4),'-',T,Y(:,5),'-.',T,Y(:,6),'.',T,Y(:,7),'-',T,Y(:,8),'-.',T,Y(:,9),'.',T,Y(:,10),'-',T,Y(:,11),'-.',T,Y(:,12),'-.',T,Y(:,13),'.',T,Y(:,14),'-',T,Y(:,15),'.') 已知X=t+1,y=2t-1 x=t+2,y=2t+1 matlab中解方程组syms x y z t[x,y,z,t]=solve(2*x+3*y-z+t-2,5*x+y+z-t-13,x-y+2*z+2*t-3,3*x+2*y+2*z+9*t+3)结果:x =-2y =1z =2t =4结果是不对的.做了如下调整：syms x y z t[t,x,y,z]=solve(2*x+3*y-z+t-2,5*x+y+z-t-13,x-y+2*z+2*t-3,3*x+2*y+2 matlab solve的用法S=dsolve('Dx=450*(90*t-x)/sqrt((90*t-x)^2+(120-y)^2),Dy=450*(120-y)/sqrt((90*t-x)^2+(120-y)^2)')结果：[y(t)=120,x(t)=450*t+C1,y(t)=120,x(t)=-450*t+C1,[((90*t-x(t))^2/diff(x(t),t)^2)^(1/2)=(90*t-x(t))/diff(x(t),t),y(t)=(120*dif 已知x=2t/1+t,y=t/1-t,用x的代数式表示y 分数的导数求法X=t/1+t Y=1+t/t X 和 Y求导分别是多少? 设x=t^2-1,y=t^4-2t^3,求y 一道定积分应用题,求曲线x=t-t*t*t 与y=1-t*t*t*t ,y x=2t+1/t,y=t-1/2t参数方程, x = t - ln(1+t) y = t^3 + t^2 求dy/dx if ( x< y ) { t=x; x=y; y=t; } 怎么理解呢?