% 四阶常微分方程与特征方程

syms c1 c2 c3 c4 x real

y = (c1+c2*x)*cos(x) + (c3+c4*x)*sin(x);

y1 = diff(y,x);
y2 = diff(y1,x);
y3 = diff(y2,x);
y4 = diff(y3,x);

disp('Result: ')
y4+2*y2+y