各位帮帮忙，给讲一讲题
matlab求2x''(t)-5x'(t)-3x(t)=90e^2t，x(0)=2，x'(0)=1，0<t<2，作x的图
syms x t;
x = dsolve('2*D2x-5*Dx+2*x=90*exp(2*t)','x(0)=2','Dx(0)=1','t');
vpa(x)
%在命令行复制出来，改写为点乘点除
t=0:0.1:2;
X=22.*exp(t./2) + 30.*t.*exp(2.*t) - 20.*exp(t./2).*exp((3.*t)./2);
plot(t,X,'o-');
grid on;