The correct option is A 3
Given A=⎡⎢⎣100101010⎤⎥⎦ satisfies
An=An−2+A2−I for n≥3 ....(1)
Now, put n=50 in (1) , we get
A50=A48+A2−I
=(A46+A2−I)+A2−I (by (1))
⇒A50=A46+2A2−2I
=(A44+A2−I)+2A2−2I (by (1))
⇒A50=A44+3A2−3I
So, we can conclude
A50=A4+23A2−23I
⇒A50=25A2−24I ...(2)
Now, A2=⎡⎢⎣100101010⎤⎥⎦⎡⎢⎣100101010⎤⎥⎦
A2=⎡⎢⎣100111101⎤⎥⎦
So, using this in (2),
A50=⎡⎢⎣250025252525025⎤⎥⎦−⎡⎢⎣240002400024⎤⎥⎦
⇒A50=⎡⎢⎣10025102501⎤⎥⎦
Trace of A50=1+1+1=3