@Carl Love Thank you very much for showing different ways how to solve my problem!! I was wondering what if I have a case like x(t)=2*a+b*t^3+2*t^2 and my IC are x(0)=1 and Dx(1)=1, so the second IC is the derivative of x with respect to t? My goal is still to find a and b. Thanks again!

@Kitonum thank you very much for your answer. I was wondering what if I have a case like x(t)=2*a+b*t^3+2*t^2 and my IC are x(0)=1 and Dx(1)=1, so the second IC is the derivative of x with respect to t? My goal is still to find a and b . Thanks again!