GATE Civil 2026 Set 2 | Question: 20

Question

A partial differential equation is given below.

\[
\frac{\partial^{2} u}{\partial x^{2}}-\frac{\partial^{2} u}{\partial y^{2}}=0
\]
Possible solution(s) is/are:

• A. $(x+y)^{5}$
• B. $(x-2 y)^{3}$
• C. $\cos (x+y)$
• D. $\sin (x-2 y)$