Understanding Transverse Wave Pulses

[bilals]

Homework Statement

2. The attempt at a solution

i thought it was number one...as we have -4.5m/s in the equation indicating that the pulse is moving in the negative direction.. i submitted the answer.unfortunately it was incorrect..

Can you help me with this..if possible.

 

[Nylex]

What about number 7? The dimensions are wrong in number one, because you have x^2 - vt, so x^2 has units of (ms^{-1})^2 and vt units of ms^{-1}.

 

[bilals]

Thank you Nylex for ur help...i submitted the answer (number 7)but...--->its wrong.
i thought again about the dimensions..i found that number two also has correct dimensions. i submitted it..and its correct.
my reasoning (not sure if it's correct)..that the negative outside the bracket when multiplied but +4.5t,becomes negative ..indicating the negative direction of the pulse.



Correct solution (Number 2)