# Toronto Math Forum

## APM346-2022S => APM346--Lectures & Home Assignments => Chapter 2 => Topic started by: Yifei Hu on February 01, 2022, 09:47:20 AM

Title: f(x) in Method of Characteristics
Post by: Yifei Hu on February 01, 2022, 09:47:20 AM
In solving the problem $2U_t+3U_x=0, U(0,x)=f(x)$, tutorial gave answer $U=f(x-\frac{3}{2}t)$ while I have $U=f(3t-2x)$. Are both answers valid? We can use different form of C as long as it represent the same family of characteristics right?
Title: Re: f(x) in Method of Characteristics
Post by: Victor Ivrii on February 01, 2022, 12:12:52 PM
Yes, there are many answers which are correct because they include arbitrary functions (and in ODE arbitrary constants)