# Math Help - Maximum displacement of particle in elastic thread

1. ## Maximum displacement of particle in elastic thread

(a) My workings:
Mg-T=M*((Mg)/(M+m))
T=Mg(1-M/(M+m))
T= $\lambda$x/l
x=(Mgl/ $\lambda$)(1-M/(M+m))
Mark Scheme:

I understood the mark scheme, but I don't understand what went wrong with my working, ie where is my logic faulty and what effect i have ignored. I would appreciate it if you can explain my mistake