Given : x=aa+b and y=ba−b
L.H.S.
=1x+1y
=a+ba+a−bb
=ab+b2+a2−abab
=a2+b2ab
=R.H.S.
If X=1+a+a2+....∞, where |a| < 1 and y=1+b+b2+.....∞ where |b| <1,
prove that 1+ab+a2b2+.....∞xyx+y−1