A) Let (√2+1)2n=I+F where I is some integer and 0≤F<1.
Then we have
√2−1=1√2+1 ⇒0<√2−1<1
⇒0<f=(√2−1)2n<1
Also ,
I+F+f=(√2−1)2n+(√2+1)2n
=2[2nC02n+2nC22n−1+.....+2nC2n]
= an even integer, say 4m+2
Therefore
⇒F+f=4m+2−I
As 0≤f<1 and 0<F<1
thus,
0<f+F<2 ⇒f+F=1
⇒I=4m+1
which is of the form 4k+1
B)
Next, as 0<2−√3=12+√3<1
Thus
(2−√3)2n=0
C) Let F1=(2−√3)2n
Also let (2−√3)2n=I1+f1, where 0≤f1<1
We have
I1+f1+F1=(2−+√3)2n+(2−√3)2n
As above f1+F1=1, therefore I1 is of the form 4k+1
D) 0<√2−1<1,(√2−1)2n=0