Hi Mandla,
Your ordinary differential equation can be written as dy/dx = x + y. To plot the differential equation you have to first solve the equation for which you can use any of the ode solvers, eg. ode45 and then use the plot function to plot the generated solution.
Here is an example code for the given ODE.
The ode45() function has the following syntax:
ode45(f, [Xi Xf], Yi);
where f is the equation in terms of variables x and y.
[Xi Xf] are the lower and upper limits of x for which equation will be integrated.
Yi is the initial value of the variable y.
[x, y] = ode45(f, [0 10], 0);
Refer to the following documentation to learn more about different types of ode solvers available:
Hope it helps!