How to plot the phase portrait of a second-order differential equation? I cannot use quiver

𝑥̈+ 𝑥̇ − 𝑥 − 𝑥 2 = 0

b. 𝑥̈+ 4𝑥̇ + 4𝑥 = 0

c. 𝑥̈− 2𝑥̇ + 2𝑥 = −8

d. 𝑥̈− 2𝑥 − 𝑥̇ − 2 = 0

I need to plot the phase portrait of these systems. What is wrong?

syms t

syms x(t)

dx=diff(x);

d2x=diff(x,2);

eq=d2x+dx-x-x.^2==0;

t=linspace(-1,1,100);

for n=1:5

s1=dsolve(eq,x(0)==n,dx(0)==n);

s2=diff(s1);

s1=subs(s1);

s2=subs(s2);

plot(s1,s2);

hold on

n=n+1;

end

Answer 1

[SaiDileep Kola]

Check the answer on similar question answered here

[Batuhan Bilen]

danke schön

Answer 2

[Shadaab Siddiqie]

From my understanding you want to plot symbolic equation. Please refer ezplot which might help you.