想請問各位大大,為何圖出不來
想了半天還想不出來><
希望各位大大能幫個忙幫我解惑...謝謝><"
U = UnitStep;
sol = DSolve[
{x''[t] + 3 x'[t] + 900 x[t] ==
100 t (U[t] - U[t - 1]) + 50 (U[t - 1] - U[t - 2]) +
100 (3 - t) (U[t - 2] - U[t - 3]), x[0] == 0, x'[0] == 0}, x[t],
t]
Plot[sol, {t, 0, 10}]