In Chapter 2 we obtained an approximate solution of the following problem, which has no analytical solution

Question:

In Chapter 2 we obtained an approximate solution of the following problem, which has no analytical solution even though it is linear.
+x = tan t................... x(0) = 0
The approximate solution, which is less accurate for large values of t, is
x(t) = 1/3 t3 -r2 + 3t -3 + 3e-t
Create a Simulink model to solve this problem and compare its solution with the approximate solution over the range 0 ≤ t ≤ l