Question

Which of the following are not the solution of \( \frac{\partial^2 z}{\partial x^2} = \frac{\partial^2 z}{\partial y^2} \)? A. \(z = f(y+x) + f(y-x)\)
B. \(z = f(y+x) + f(y-x)\)
C. \(z = f(x^2 - y^2)\)
D. \(z = f(x^2 + y^2)\)

• A. A, B and C only
• B. B, C and D only
• C. A, C and D only
• D. A, B and D only

Hint:

Wave-type PDE → solution depends on \(x+y\) and \(x-y\).

Answer 1

The Correct Option is B