The displacement of particles in a string stretched in the x-direction is represented by y.among the following expressions for y, those describing wave motion are

Options

A. `cos kx sin omega t`
B. `k^2 x^2 - omega^2 t^2`
C. `cos^2(kx + omega t)`
D. `cos (k^2 x^2 - omega^2 t^2)`

Answer

A, C

Explanation

`(del^(2)y)/(del x^(2)) = ("constant") (del^(2)y)/(del t^(2))`.