The '2' is from the original 2q.
I don't get what you mean about my differentiation at the end, i have not differentiated yet.
Where am i going wrong ?
So is it this line that is wrong? q=(5(2e(2t)sin(t)+e(2t)cos(t))+C/2e(2t)
Should it be q=5(2e(2t)sin(t)+e(2t)cos(t))+C/e(2t)
which would cancel down to q=5(e(2t)sin(t)+cos(t))+C wouldn't it ?????